open sesame 1 magic words spoken to open the door of the thieves' den in the story of Ali Baba in The Arabian Nights 2 any unfailing means of gaining admission or achieving some other end

open shop 1 a factory, business, etc. employing workers without regard to whether or not they are members of a union with which it may have a contract; also, the policy of employing workers in this way

open stock merchandise, as dishes, available in sets, with individual pieces kept in stock for replacements or additions

open-and-shut (ou´pэn эn shût´) •adj. that can clearly and easily be determined or decided; very simple or obvious {an open-and-shut case}

open-end (ou´pэn end´) •adj. 1 of or pertaining to an investment company that has no fixed limit to the number of shares issued, so that the shares are issued and redeemed as demand requires 2 allowing the borrowing of additional funds over a period of time on the original security 3 OPEN-ENDED

open-ended (-en´did) •adj. 1 having no set limits as to duration, direction, amount, number, etc.; broad, unlimited, or unrestricted {an open-ended discussion} 2 open to change; allowing for modifications as things develop 3 designating or of a question allowing for a freely formulated answer rather than one made by a choice from among predetermined answers o´pen-end´ed·ness •n.

opener (o´pэn эr) •n. 1 a person or thing that opens 2 any of several devices for opening bottles, cans, etc. 3 the first game in a series, the first act in a vaudeville show, etc. Æ 4 [pl.] Poker cards of sufficient value to allow a player to open the betting for openers [Colloq.] to begin with

open-eyed (ou´pэn aid') •adj. 1 having the eyes open or wide open; awake, aware, watchful, discerning, amazed, etc. 2 done with the eyes open

open-faced (o´pэn feist', -feist´) •adj. 1 with the face uncovered 2 having a frank, honest face Æ 3 designating a sandwich without a top slice of bread: also o´pen-face'

openhanded (-hæn'did) •adj. generous o´pen·hand'ed·ly •adv. o´pen·hand'ed·ness •n.

open-heart surgery (-härt´) surgery involving some type of repair directly to the exposed heart or coronary arteries, etc., during which the blood is diverted and circulated and oxygenated by mechanical means

openhearted (-härt'id) •adj. 1 not reserved; frank; candid 2 kindly; generous o´pen·heart'ed·ly •adv. o´pen·heart'ed·ness •n.

open-hearth (ou´pэn härθ´) •adj. 1 designating a furnace with a wide, saucer-shaped hearth and a low roof, used in making steel 2 using a furnace of this kind {the open-hearth process}

opening (ou´pэ niŋ'; often oup´niŋ') •n. 1 a becoming open or causing to be open 2 an open place or part; hole; gap; aperture Æ 3 a clearing in the midst of a wooded area 4 a) a beginning; first part; commencement b) start of operations; formal beginning c) a first performance, as of a play 5 a favorable chance or occasion; opportunity 6 an unfilled position or office for which a person is wanted 7 Chess, Checkers the series of moves at the beginning of a game, often a specific, conventional sequence of moves [ME openyng]

open-minded (ou´pэn main´did) •adj. having a mind that is open to new ideas; free from prejudice or bias o´pen-mind´ed·ly •adv. o´pen-mind´ed·ness •n.

open-mouthed (-mauðd', -mauθt') •adj. 1 having the mouth open 2 gaping, as in astonishment 3 clamorous

open-pollination (ou'pэn päl'э nei´shэn) •n. the pollination of open flowers by insects, the wind, etc. without human action

openwork (ou´pэn wørk') •n. ornamental work, as in cloth, metal, etc., with openings in the material

opéra bouffe (ô pei řå bu:f´; E äp´эr э bu:f´) comic, esp. farcical, opera Also o·pe·ra buf·fa (ô´pe řä bu:f´fä') [Fr]

opéra comique (ô pei řå kô mi:k´) French opera with some spoken dialogue: it may or may not be comic [Fr, comic opera]

opera glasses a small binocular telescope used at the opera, in theaters, etc.

opera hat a man's tall, collapsible silk hat

opera house a theater chiefly for the performance of operas

opera seria (ô´pe řä se´ři: ä; E äp´эr э ser´i: э, -sir´-) 18th-cent. opera characterized by the stylized treatment of mythological or classical subjects and the extensive use of arias [It, serious opera]

opera¹ (äp´эr э; often äp´rэ) •n. 1 a play having all or most of its text set to music, with arias, recitatives, choruses, duets, trios, etc. sung to orchestral accompaniment, usually characterized by elaborate costuming, scenery, and choreography: see GRAND OPERA, COMIC OPERA 2 the branch of art represented by such plays 3 the score, libretto, or performance of such a play 4 a theater in which operas are given [It < L, a work, labor, akin to opus: see OPUS]

opera² (ou´pэ rэ, äp´э rэ) •n. pl. of OPUS

operable (äp´эr э bэl) •adj. 1 practicable or feasible 2 able to function or be operated, as a machine 3 that can be treated by a surgical operation op'er·a·bil´i·ty •n. op´er·a·bly •adv. [ML operabilis: see OPERATE & -ABLE]

operand (äp´эr ænd') •n. Math. that which is operated upon by an operator [< L operandum, neut. ger. of operari, to work: see OPERATE]

operant (äp´эr эnt) •adj. 1 operating, or producing an effect or effects 2 Psychol. a) designating behavior defined by the resulting stimulus rather than the stimulus which elicits it b) designating conditioning in which the desired response, when it occurs, is reinforced by a stimulus •n. a person or thing that operates [< L operans, prp. of operari: see OPERATE]

operate (äp´эr eit') -at'ed, -at'ing •vi. 1 to be in action so as to produce an effect; act; function; work 2 to bring about a desired or appropriate effect; have a certain influence 3 to carry on strategic military movements 4 to perform a surgical operation •vt. 1 [Now Rare] to bring about as an effect 2 a) to put or keep in action; work (a machine, etc.) b) to conduct or direct the affairs of (a business, etc.); manage 3 [Colloq.] to perform a surgical operation on [< L operatus, pp. of operari, to work < opus (gen. operis): see OPUS]

operatic (äp'эr æt´ik) •adj. of or like the opera op'er·at´i·cal·ly •adv. [OPERA¹ + (DRAMA)TIC]

operation (äp'эr ei´shэn) •n. 1 the act, process, or method of operating 2 the condition of being in action or at work 3 a process or action that is part of a series in some work 4 a) any movement or series of movements made in carrying out strategic military plans b) [pl.] a center where such activities are monitored or supervised, as at an air base c) any specific plan, project, venture, etc. {Operation Cleanup} 5 any surgical procedure performed, usually with the aid of instruments, to remedy a physical ailment or defect 6 Math. any process, as addition, division, etc., involving a change or transformation in a quantity in operation 1 in the act or process of making, working, etc. 2 having an influence or effect; in force [ME operacion < OFr < L operatio]

operational (äp'эr ei´shэ nэl) •adj. 1 of, having to do with, or derived from the operation of device, system, process, etc. 2 a) that can be used or operated b) in use; operating 3 of or ready for use in a military operation op'er·a´tion·al·ly •adv.

operationalism (-shэ nэl iz'эm) Philos. the doctrine that no concept or term used in a purportedly factual statement has valid meaning unless it can be defined in terms of repeatable, empirical operations, experimental procedures, etc. Also op'er·a´tion·ism' •n. op'er·a´tion·al·ist •n. op'er·a'tion·al·is´tic •adj.

operationalize (-shэ nэl aiz') -ized', -iz'ing •vt. to make operational; put into operation op'er·a'tion·al·i·za´tion •n.

operations research the systematic and scientific analysis and evaluation of problems, as in government, military, or business operations Also operations analysis

operative (äp´эr э tiv', -эr eit'iv) •adj. 1 capable of, characterized by, or in operation 2 accomplishing what is desired; effective 3 connected with physical work or mechanical action 4 Surgery of or resulting from a surgical operation •n. 1 a worker, esp. one skilled in industrial work Æ 2 a detective or spy op´er·a'tive·ly •adv. [Fr opératif < LL(Ec) operativus]

operator (äp´эr æt'эr) •n. 1 a person who operates; specif., a) a person who effects something; agent Æ b) a person who works some machine {a telephone operator} c) a person who performs surgical operations Æ d) a person engaged in financial, commercial, or industrial operations; owner or manager of a mine, railroad, factory, etc. Æ 2 [Slang] a clever, persuasive person who generally manages to achieve his or her ends 3 Math. any symbol or term conventionally indicating that a certain process, substitution, etc. is to be carried out

opercular (ou pør´kyu: lэr, -kyэ-) •adj. of, or having the nature of, an operculum

operculate (-lit, -leit') •adj. having an operculum: also o·per´cu·lat'ed [L operculatus]

operculum (ou pør´kyu: lэm, -kyэ-) pl. -la (-kyэ-) •n.or -lums any of various covering flaps or lidlike structures in plants and animals; specif., a) the bony covering protecting the gills of fishes b) in many gastropods, the horny plate serving to close the shell when the animal is retracted c) the lid of spore cases in mosses d) the lid of a pitcher-shaped leaf [ModL < L, lid, dim. < operire, to close, shut: for IE bases see OB- & APERTURE]

operetta (äp'эr et´э) •n. a light, amusing opera with spoken dialogue [It, dim. of opera, OPERA¹]

operon (äp´эr än') •n. a cluster of genes, with related functions acting as a coordinated unit controlled by a regulatory gene [< L operare, to work (see OPERATE) + -ON]

operose (äp´эr ous') •adj. [Archaic] 1 done with or requiring much toil 2 very busy; industrious [L operosus < opus (gen. operis), work: see OPUS]

Ophelia (ou fi:l´yэ) 1 a feminine name 2 in Shakespeare's Hamlet, Polonius's daughter, in love with Hamlet [prob. < Gr ōphelia, a help, succor]

ophicleide (äf´i klaid') •n. an early brass instrument consisting of a long tube doubled back on itself, with keys for fingering [Fr ophicléide < Gr ophis (see OPHIOLATRY) + kleis, a key: for IE base see LOT]

ophidian (ou fid´i: эn) •n. a snake or serpent •adj. of or like a snake [< ModL Ophidia, former name of the suborder Serpentes (< Gr ophis): see OPHIOLATRY + -AN]

ophiolatry (äf'i: äl´э tri:) •n. the worship of serpents [< Gr ophis, a snake (< IE *ogiohi-, akin to base *eghi-, snake > Arm iž, viper) + -LATRY]

ophiolite (äf´i: э lait, ou´fi:-) •n. a widespread rock formation containing a mixture of sedimentary, igneous, and metamorphic rocks, thought to be the result of sea-floor rifting or crustal plate collisions

ophiology (äf'i: äl´э ji:) •n. the branch of zoology dealing with snakes oph'i·o·log´ic (-э läj´ik) or oph'i·o·log´i·cal •adj. oph'i·ol´o·gist •n. [< Gr ophis, a snake (see OPHIOLATRY) + -LOGY]

Ophir (ou´fэr) Bible a land rich in gold: 1 Kings 9:28; 10:11; 2 Chron. 8:18 [Heb ōphīr]

ophitic (ou fit´ik) •adj. designating a texture of rock, characteristic of dolerites, in which long, flat, narrow crystals of plagioclase feldspar are embedded in augite [< L ophites < Gr ophitēs (lithos), snake (stone) < ophis, a snake (see OPHIOLATRY) + -IC]

Ophiuchus (äf'i: yu:´kэs, ou'fi:-) a large N and S constellation between Hercules and Scorpius [L < Gr ophiouchos, lit., holding a serpent < ophis (see OPHIOLATRY) + base of echein, to hold: see SCHEME]

ophthalmia (äf θæl´mi: э) •n. a severe inflammation of the eyeball or conjunctiva Also oph·thal·mi·tis (äf'θæl mait´is, -θэl-) [ME obtalmia < LL ophthalmia < Gr < ophthalmos, the eye: see OPHTHALMO-]

ophthalmic (äf θæl´mik) •adj. of or connected with the eye [LL ophthalmicus < Gr ophthalmikos < ophthalmos: see OPHTHALMO-]

ophthalmo- (äf θæl´mou, -mэ) combining form the eye or eyes {ophthalmoscope} Also, before a vowel, oph·thalm´- [< Gr ophthalmos, akin to ōps, EYE]

ophthalmology (äf'θæl mäl´э ji:, -θэl-; often, äp'-) •n. the branch of medicine dealing with the structure, functions, and diseases of the eye oph'thal·mo·log´i·cal (-mou läj´i kэl, -mэ-) •adj. oph'thal·mol´o·gist •n. [prec. + -LOGY]

ophthalmoscope (äf θæl´mэ skoup') •n. an instrument used to examine the interior of the eye: it consists of a perforated mirror arranged to reflect light from a small bulb into the eye oph·thal'mo·scop´ic (-skäp´ik) •adj. oph·thal·mos·co·py (äf'θæl mäs´kэ pi:, -θэl-) •n. [OPHTHALMO- + -SCOPE]

-opia (ou´pi: э) combining form a (specified) condition or defect of the eye {hypermetropia} [Gr -ōpia < ōps, EYE]

opiate (for n. ou´pi: it, -eit'; for v., -eit') •n. 1 any medicine containing opium or any of its derivatives, and acting as a sedative and narcotic 2 anything tending to quiet, soothe, or deaden •adj. 1 containing opium 2 bringing sleep, quiet, or ease; narcotic •vt. -at'ed, -at'ing 1 [Rare] to treat with an opiate 2 to dull; deaden [ML opiatum: see OPIUM]

opine (ou pain´) o·pined´, o·pin´ing •vt., vi. to hold or express (an opinion); think; suppose: now usually humorous [MFr opiner < L opinari, to think: see OPINION]

opinion (э pin´yэn, ou-) •n. 1 a belief not based on absolute certainty or positive knowledge but on what seems true, valid, or probable to one's own mind; judgment 2 an evaluation, impression, or estimation of the quality or worth of a person or thing 3 the formal judgment of an expert on a matter in which advice is sought 4 Law the formal statement by a judge, court referee, etc. of the law bearing on a case SYN.—opinion applies to a conclusion or judgment which, while it remains open to dispute, seems true or probable to one's own mind [it's my opinion that he'll agree]; belief refers to the mental acceptance of an idea or conclusion, often a doctrine or dogma proposed to one for acceptance [religious beliefs]; a view is an opinion affected by one's personal manner of looking at things [she gave us her views on life]; a conviction is a strong belief about whose truth one has no doubts [I have a conviction of your innocence]; sentiment refers to an opinion that is the result of deliberation but is colored with emotion; persuasion refers to a strong belief that is unshakable because one wishes to believe in its truth [ME opinioun < OFr < L opinio < opinari, to think, akin to optare, to select, desire: see OPTION]

opinionated (-eit'id) •adj. holding unreasonably or obstinately to one's own opinions o·pin´ion·at'ed·ly •adv. o·pin´ion·at'ed·ness •n.

opinionative (-eit'iv, -э tiv) •adj. 1 of, or having the nature of, opinion 2 OPINIONATED o·pin´ion·a'tive·ly •adv. o·pin´ion·a'tive·ness •n.

opisthognathous (äp'is θäg´nэ θэs) •adj. having receding jaws, as certain insects [< Gr opisthen, behind (< IE *opi-: see OB-) + -GNATHOUS]

opium (ou´pi: эm) •n. 1 a yellow to dark brown, addicting, narcotic drug prepared from the juice of the unripe seed capsules of the opium poppy: it contains such alkaloids as morphine, codeine, and papaverine, and is used as an intoxicant and medicinally to relieve pain and produce sleep 2 anything that has a tranquilizing or stupefying effect [L < Gr opion < opos, vegetable juice < IE base *s(w)ekwos-, plant juice > OProv sackis]

opium poppy an annual poppy (Papaver somniferum) with grayish-green leaves and large, white or purple flowers, the source of opium

opiumism (-iz'эm) •n. 1 opium addiction 2 the condition resulting from this

Oporto (ou pör´tou) seaport in N Portugal, on the Douro River: pop. 330,000: Port. name PÔRTO

opossum (э päs´эm) pl. -sums •n.or -sum any of various families (esp. Didelphidae) of marsupials; esp., any of a small, omnivorous, tree-dwelling American species (Didelphis marsupialis) with a ratlike, prehensile tail, that is active at night and becomes motionless when endangered [< AmInd (Algonquian) name, lit., white beast]

opossum shrimp MYSID: the female carries her eggs in a pouch between the legs

opp 1 opposed 2 opposite

Oppenheimer (äp´ªn hai'mэr), J(ulius) Robert 1904-1967; U.S. nuclear physicist

oppidan (äp´i dэn) •adj. of a town; urban •n. a person living in a town [L oppidanus < oppidum, town]

oppilate (äp´э leit') -lat'ed, -lat'ing •vt. [Rare] to block or obstruct (the pores, bowels, etc.) op'pi·la´tion •n. [< L oppilatus, pp. of oppilare, to stop up < ob- (see OB-) + pilare, to ram down < pilum, pestle]

opponency (э pou´nэn si:) •n. opposition; resistance

opponent (э pou´nэnt) •n. a person who opposes; person against one in a fight, game, debate, argument, etc.; adversary •adj. 1 [Rare] opposite, as in position 2 opposing; adverse; antagonistic 3 Anat. bringing parts into opposition: said of a muscle SYN.—opponent, an unemotional word, refers to anyone who is opposed to one, as in a fight, game, debate, etc.; antagonist implies more active opposition, especially in a struggle for control or power; adversary usually suggests actual hostility in the conflict; enemy may imply actual hatred in the opponent and a desire to injure, or it may simply refer to any member of the opposing group, nation, etc., whether or not there is personal animosity or hostility involved; foe, now a somewhat literary synonym for enemy, connotes more active hostility —ANT. ally, confederate [< L opponens, prp. of opponere < ob- (see OB-) + ponere, to place: see POSITION]

opportune (äp'эr tu:n´, -tyu:n´) •adj. 1 right for the purpose; fitting in regard to circumstances: said of time 2 happening or done at the right time; seasonable; well-timed; timely SYN. TIMELY op'por·tune´ly •adv. op'por·tune´ness •n. [ME < MFr < L opportunus, lit., at or before the port < ob- (see OB-) + portus, PORT¹]

opportunism (-iz'эm) •n. the practice or policy of adapting one's actions, judgments, etc. to circumstances, as in politics, in order to further one's immediate interests, without regard for basic principles or eventual consequences op'por·tun´ist •n., adj. op'por·tun·is´tic •adj. op'por·tun·is´ti·cal·ly •adv. [Fr opportunisme]

opportunity (äp'эr tu:´nэ ti:, -tyu:´-) pl. -ties •n. 1 a combination of circumstances favorable for the purpose; fit time 2 a good chance or occasion, as to advance oneself [ME opportunite < OFr opportunité < L opportunitas < opportunus: see OPPORTUNE]

opposable (э pou´zэ bэl) •adj. 1 that can be opposed 2 that can be placed opposite something else, as the thumb with each finger op·pos'a·bil´i·ty •n.

oppose (э pouz´) -posed´, -pos´ing •vt. 1 to set against; place opposite, in balance or contrast 2 to contend with in speech or action; resist; withstand •vi. to act in opposition op·pos´er •n. [ME opposen < OFr opposer, altered (infl. by poser: see POSE¹) < L opponere: see OPPONENT]

opposite (äp´э zit, -sit) •adj. 1 set against, facing, or back to back; at the other end or side; in a contrary position or direction: often with to 2 characterized by hostility or resistance 3 different in every way; exactly contrary; antithetical 4 Bot. a) growing in pairs, but separated by a stem b) having one part on the same radius as another, as a stamen in front of a petal •n. anything opposed or opposite •adv. on opposing sides or in an opposite position •prep. 1 fronting; across from 2 Theater in a complementary role (of the opposite sex) to {he played opposite her} op´po·site·ly •adv. op´po·site·ness •n. SYN.—opposite is applied to things that are symmetrically opposed in position, direction, etc. [they sat at opposite ends of the table]; contrary adds to this connotations of conflict or antagonism [they hold contrary views]; antithetical implies diametrical opposition so that the contrasted things are as far apart or as different as is possible [our interests are completely antithetical]; reverse applies to that which moves or faces in the opposite direction [the reverse side of a fabric]; antonymous is used specifically of words that are so opposed in meaning that each contradicts, reverses, or negates the other [good and bad are antonymous terms] —ANT. same, identical, like [OFr < L oppositus, pp. of opponere: see OPPONENT]

opposite number a person with reference to another having a comparable position, rank, etc. but in a different place, organization, or situation

opposition (äp'э zish´эn) •n. 1 the act of opposing 2 an opposed condition; resistance, contradiction, contrast, hostility, etc. 3 a) any person, group, or thing that opposes b) [often O-] a political party opposing, and serving as a check on, the party in power 4 Astrol., Astron. the position of two celestial bodies when their celestial longitudes differ by 180 °; esp., the position of a superior planet or the full moon when it is in opposition with the sun 5 Law the refusal of a creditor to assent to a debtor's release under the bankruptcy law 6 Logic the relation of exclusion or inclusion which exists between propositions having the same subject and predicate but differing in quality, quantity, or both op'po·si´tion·al •adj. op'po·si´tion·ist •n., adj. [ME opposicioun < OFr opposition < L oppositio < oppositus, pp. of opponere: see OPPONENT]

oppress (э pres´) •vt. 1 to weigh heavily on the mind, spirits, or senses of; worry; trouble 2 to keep down by the cruel or unjust use of power or authority; rule harshly; tyrannize over 3 [Obs.] a) to crush; trample down b) to overpower; subdue SYN. WRONG op·pres´sor •n. [ME oppressen < OFr oppresser < ML oppressare < L oppressus, pp. of opprimere, to press against < ob- (see OB-) + premere, PRESS¹]

oppression (э presh´эn) •n. 1 an oppressing or being oppressed 2 a thing that oppresses 3 a feeling of being weighed down, as with worries or problems; physical or mental distress [OFr < L oppressio]

oppressive (э pres´iv) •adj. 1 hard to put up with; causing great discomfort or fatigue 2 cruelly overbearing; tyrannical 3 weighing heavily on the mind, spirits, or senses; distressing SYN. ONEROUS op·pres´sive·ly •adv. op·pres´sive·ness •n. [ME oppressivus < L oppressus: see OPPRESS]

opprobrious (э prou´bri: эs) •adj. 1 expressing opprobrium; abusive; disrespectful 2 [Now Rare] deserving opprobrium; disgraceful op·pro´bri·ous·ly •adv. op·pro´bri·ous·ness •n. [ME < LL opprobriosus]

opprobrium (э prou´bri: эm) •n. 1 the disgrace or infamy attached to conduct viewed as grossly shameful 2 anything bringing shame or disgrace 3 reproachful contempt for something regarded as inferior [L < opprobrare, to reproach < ob- (see OB-) + probrum, a disgrace < pro- (see PRO-²) + *bhrom < base of ferre, BEAR¹, formed after Gr propherein, to bring forward, allege, reproach]

oppugn (э pyu:n´) •vt. to oppose with argument; criticize adversely; call in question; controvert op·pugn´er •n. [ME oppugnen < L oppugnare < ob- (see OB-) + pugnare < pugna, a fight: see PUGNACIOUS]

oppugnant (э pûg´nэnt) •adj. [Rare] hostile; antagonistic op·pug´nan·cy •n. [L oppugnans, prp.: see OPPUGN]

O-proposition (ou´präp'э zish´эn) •n. Logic a particular negative proposition

Ops (äps) Rom. Myth. the wife of Saturn and goddess of the harvest: identified with the Greek Rhea [L, lit., strength, riches: for IE base see OPUS]

-opsis (äp´sis) combining form sight or view {stereopsis} [Gr -opsis < opsis, a sight < ōps, EYE]

opsonic index the ratio of the number of bacteria destroyed by phagocytes in an individual's blood serum to the number destroyed in a normal blood serum [see OPSONIN]

opsonify (äp sän´э fai') -fied', -fy'ing •vt. OPSONIZE op·son'i·fi·ca´tion •n.

opsonin (äp´sэ nin) •n. a substance in blood serum acting on bacteria and foreign cells to make them more liable to destruction by phagocytes op·son´ic (-sän´ik) •adj. [obs. opson(ium), relish (< L < Gr opsōnion, food, provisions < opsōnein, to buy food < opson, meat or any food eaten with bread < o-, together with + *psōn, food, bread, akin to psōmos, mouthful) + -IN¹]

opsonize (äp´sэ naiz') -nized', -niz'ing •vt. to make bacteria more liable to destruction by phagocytes op'so·ni·za´tion •n. [see OPSONIN]

opt (äpt) •vi. to make a choice: often with for opt out (of) to choose not to be or continue in (some activity, organization, etc.) [Fr opter < L optare: see OPTION] opt abbrev. 1 optical 2 optician 3 optics 4 optional

optative (äp´tэ tiv) •adj. 1 expressing wish or desire 2 designating or of the grammatical mood, as in Greek, which expresses wish or desire •n. 1 the optative mood 2 a verb in this mood op´ta·tive·ly •adv. [Fr optatif < LL optativus < pp. of L optare: see OPTION]

optic (äp´tik) •adj. of the eye or sense of sight •n. an eye: a pretentiously humorous usage, generally in the pl. [MFr optique < ML opticus < Gr optikos < optos, seen < ōps, EYE]

optic axis in anisotropic crystals, a direction along which the velocity of light does not depend on the polarization of the light

optic disk BLIND SPOT (sense 1)

optic nerve either of the second pair of cranial nerves, which connect the retina of the eye with the brain: see EYE, illus.

optical (äp´ti kэl) •adj. 1 of or connected with the sense of sight; visual; ocular 2 of the relation between light and vision 3 having to do with optics 4 for aiding vision {optical instruments} op´ti·cal·ly •adv.

optical activity the ability of certain substances to rotate the plane of polarization when transmitting polarized light

optical double (star) DOUBLE STAR (sense 2)

optical isomerism a type of isomerism in which isomeric compounds differ only in the direction in which they rotate the plane of polarized light

optician (äp tish´эn) •n. a person who makes or deals in optical instruments, esp. one who prepares and dispenses eyeglasses [Fr opticien]

optics (äp´tiks) •n.pl. [with sing. v.] the branch of physics dealing with the nature and properties of light and vision [< OPTIC]

optimal (äp´tэ mэl) •adj. most favorable or desirable; best; optimum op´ti·mal·ly •adv. [OPTIM(UM) + -AL]

optimism (äp´tэ miz'эm) •n. 1 Philos. a) the doctrine held by Leibniz and others that the existing world is the best possible b) the doctrine or belief that good ultimately prevails over evil 2 the tendency to take the most hopeful or cheerful view of matters or to expect the best outcome; practice of looking on the bright side of things op´ti·mist (-mist) •n. op'ti·mis´tic (-mis´tik) or op'ti·mis´ti·cal •adj. op'ti·mis´ti·cal·ly •adv. [Fr optimisme < L optimus, best: see OPTIMUM]

optimize (äp´tэ maiz') -mized', -miz'ing •vi. to be given to optimism •vt. to make the most of; develop or realize to the utmost extent; obtain the most efficient or optimum use of op'ti·mi·za´tion •n.

optimum (äp´tэ mэm) pl. -mums or -ma (-mэ) •n. 1 the best or most favorable degree, condition, amount, etc. 2 Biol. the amount of heat, light, moisture, food, etc. most favorable for growth and reproduction •adj. most favorable or desirable; best; optimal [L, neut. of optimus, best < ops, power, riches: for IE base see OPUS]

option (äp´shэn) •n. 1 the act of choosing; choice 2 the power, right, or liberty of choosing 3 something that is or can be chosen; choice 4 the right, acquired for a consideration, to buy, sell, or lease something at a fixed price, sign or renew a contract, etc. within a specified time Sports to transfer (a player) to a minor league with the option of recalling him •vt. SYN. CHOICE [Fr < L optio < optare, to wish, desire, ult. < IE *op-, to choose, prefer]

optional (äp´shэ nэl) •adj. left to one's option, or choice; not compulsory; elective op´tion·al·ly •adv.

opto- (äp´tou, -tэ) combining form pertaining to sight or vision; optical {optometry, optoelectronics}

optoacoustic (äp'tou э kus´tik) •adj. of an effect, technique, etc. in which light, as a laser beam, generates sound waves in a gas or other medium

optoelectronics (äp'tou i:'lek'trän´iks) •n.pl. a branch of electronics involving the use of optical technology op'to·e'lec'tron´ic •adj.

optometer (äp täm´эt эr) •n. an instrument for determining error in the refractive power of the eye [see OPTIC & -METER]

optometrist (äp täm´э trist') •n. a specialist in optometry

optometry (äp täm´э tri:) •n. 1 measurement of the range and power of vision 2 the profession of examining the eyes and measuring errors in refraction and of prescribing glasses to correct these defects op·to·met·ric (äp'tэ met´rik) or op'to·met´ri·cal •adj. [see OPTIC & -METRY]

opulent (äp´yu: lэnt, -yэ-) •adj. 1 very wealthy or rich 2 characterized by abundance or profusion; luxuriant SYN. RICH op´u·lence or op´u·len·cy •n. op´u·lent·ly •adv. [L opulentus or opulens < ops: see OPUS]

opuntia (ou pûn´shi: э, -shэ) •n. any of a large genus (Opuntia) of cactus plants with red, purple, or yellow flowers, pulpy or dry berries, and fleshy, jointed stems, including the prickly pears and chollas [ModL < L (herba) Opuntia, (plant) of Opus, city in LOCRIS]

opus (ou´pэs) pl. o·pe·ra (ou´pэ rэ, äp´э rэ) •n.or o´pus·es a work; composition; esp., any of the musical works of a composer numbered in order of composition or publication [L, a work < IE *ops < base *op-, to work, riches > L ops, riches, Sans ápas-, work, OE efnan, to work, do]

opuscule (ou pûs´kyu:l') •n. [Rare] a minor work, as of literature o·pus´cu·lar •adj. [Fr < L opusculum, dim. of opus: see OPUS]

-opy (ou´pi:) combining form -OPIA

OR 1 operating room 2 Oregon

-or (эr, ör) suffix 1 a person or thing that (does a specified thing) {mortgagor, incisor} [ME -our < OFr -our, -or, -eur < L -or, -ator] 2 quality or condition {favor, error} [ME -our < OFr < L -or] USAGE—for several words with this suffix, e.g. ardor, armor, color, endeavor, favor, honor, labor, rumor, savior, the spelling -our is standard usage or a common alternate spelling in most other English-speaking countries (ardour, armour, colour, etc.); other words, e.g. error, liquor, pallor, terror, are now always spelled with -or

or¹ (ör; unstressed, эr) conj. a coordinating conjunction introducing an alternative; specif., a) introducing the second of two possibilities {beer or wine} b) introducing any of the possibilities in a series, but usually used only before the last {apples, (or) pears, or plums} c) introducing a synonymous word or phrase {botany, or the science of plants} d) introducing the second of two possibilities when the first is introduced by either or whether {either go or stay, whether to go or stay} e) [Old Poet.] substituted for either or whether as the first correlative {or in the heart or in the head} [ME, in form a contr. of other, auther, either, but actually < OE oththe (in āther ... oththe, either ... or)]

or² (ör) conj., prep. [Now Chiefly Dial.] before; ere [ME < OE ār, var. of ær, ere: see ERE]

or³ (ör) •n. Heraldry the representation of the metal gold: indicated in engravings by small black dots on a white field [Fr < L aurum, gold: for IE base see EAST]

ora (ou´rэ; our´э, ör´э) •n. pl. of OS²

orach or orache (ör´эch, är´-) •n. any of a genus (Atriplex) of plants of the goosefoot family, widespread in salty or alkaline areas, having usually silvery foliage and small green flowers; esp., garden orach (A. hortensis), cultivated as a potherb, chiefly in France [ME orage < Anglo-Fr orache < OFr arroche < VL *atrapica (for L atriplex) < Gr atraphaxys]

oracle (ör´э kэl, är´-) •n. 1 among the ancient Greeks and Romans, a) the place where, or medium by which, deities were consulted b) the revelation or response of a medium or priest 2 a) any person or agency believed to be in communication with a deity b) any person of great knowledge or wisdom c) opinion or statements of any such oracle 3 the holy of holies of the ancient Jewish Temple: 1 Kings 6:16, 19-23 [OFr < L oraculum, divine announcement, oracle < orare, to speak, pray, beseech < os (gen. oris), the mouth: see ORAL]

oracular (ou ræk´yu: lэr, -yэ-; э ræk´-, ö-) •adj. 1 of, or having the nature of, an oracle 2 like an oracle; wise, prophetic, mysterious, etc. 3 obscure; enigmatic o·rac'u·lar´i·ty (-yu: lær´э ti:, -yэ-) •n. o·rac´u·lar·ly •adv.

orad (ou´ræd'; our´æd', ör´-) •adv. toward the mouth or oral region [< L os (gen. oris), the mouth + -AD²]

Oradea (ô řäd´yä) city in NW Romania, near the Hungarian border: pop. 198,000

oral (our´эl, ou´rэl; ör´-) •adj. 1 uttered by the mouth; spoken 2 of speech; using speech 3 of, at, or near the mouth 4 Phonet. having mouth resonance only: distinguished from NASAL 5 Psychoanalysis a) designating or of the earliest stage of psychosexual development in which interest centers around sucking, feeding, and biting b) designating or of such traits in the adult as friendliness, generosity, and optimism or aggressiveness and pessimism, regarded as unconscious psychic residues of that stage (cf. ANAL, GENITAL) 6 Zool. on or of the same side as the mouth Æ n. an examination with spoken questions and answers, as at a college: often used in pl. o´ral·ly •adv. SYN.—oral refers to that which is spoken, as distinguished from that which is written or otherwise communicated [an oral promise, request, etc.]; verbal, though sometimes synonymous with oral, in strict discrimination refers to anything using words, either written or oral, to communicate an idea or feeling [a verbal image, caricature, etc.] [< L os (gen. oris), the mouth < IE base *ōus-, mouth, edge > Sans a-h, mouth, ON ōss, mouth of a stream]

oral history 1 historical data consisting of personal recollections, usually in the form of a tape-recorded interview 2 the gathering and preservation of such data 3 a historical account based on such data

oral surgery a branch of dentistry dealing with surgery for disorders and diseases of the teeth, gums, and jaws oral surgeon

oralism (our´эl iz'эm, ou´rэl-, ör´-) •n. the theory or practice of teaching deaf people to communicate primarily or exclusively through lip-reading and speaking rather than signing o´ral·ist •adj., n.

-orama (э ræm´э, -räm´э) combining form a greater-than-usual number, volume, or variety of a specified thing: used to form commercial names and other words for events and displays {sportorama}: also -o-ram´a

Oran (ou ræn´; Fr ô řän´) seaport in N Algeria, on the Mediterranean: pop. 660,000

orang (ou ræŋ´, ö-, э-) •n. ORANGUTAN

orange (ör´inj, är´-; often örnj, ärnj) •n. 1 a reddish-yellow, round, edible citrus fruit, with a sweet, juicy pulp 2 any of various evergreen trees (genus Citrus) of the rue family producing this fruit, having white, fragrant blossoms and hard, yellow wood 3 any of several plants or fruits resembling the orange 4 reddish yellow •adj. 1 reddish-yellow 2 made with or from an orange or oranges 3 having a flavor like that of oranges [OFr orenge < Prov auranja (with sp. infl. by L aurum, gold, & loss of initial n through faulty separation of art. un) < Sp naranja < Ar nāranj < Pers nārang < Sans naranga, prob. akin to Tamil naru, fragrant] Orange (ör´inj, är´-) name of the ruling family of the Netherlands: see NASSAU •adj. of or having to do with Orangemen Orange (ör´inj, är´-; also, for 3 & 4, Fr ô řäñzh´) 1 city in SW Calif.: suburb of Los Angeles: pop. 111,000 [prob. named for the orange groves there] 2 river in South Africa, flowing from NE Lesotho west into the Atlantic: c. 1,300 mi. (2,092 km) 3 former principality of W Europe (12th-17th cent.), now in SE France 4 city in SE France: pop. 27,000

Orange Free State province of South Africa, west of Lesotho: formerly a Boer republic (1854-1900) & then a British colony (Orange River Colony, 1900-10): 49,418 sq. mi. (127,993 sq. km); pop. 1,932,000; cap. Bloemfontein

orange hawkweed DEVIL'S PAINTBRUSH

orange pekoe a black tea of Sri Lanka and India: see PEKOE

orange roughy (rûf´i:) pl. rough|y a bright reddish-orange food fish (Hoplostethus atlanticus) of an order (Beryciformes, family Trachichthyidae) of deep-sea bony fishes with primitive bony rays

orange stick a pointed stick, orig. of orangewood, used in manicuring

orangeade (ör'inj eid´; often örnj'eid´) •n. a drink made of orange juice and water, usually sweetened [Fr: see ORANGE & -ADE]

Orangeman (-mэn) pl. -men (-mэn) a member of a secret Protestant society organized in Northern Ireland (1795) •n. [after the Prince of Orange, later WILLIAM III]

orangery (ör´inj ri:, är´-) pl. -ries •n. a hothouse or other sheltered place for growing orange trees in cooler climates [Fr orangerie < oranger, orange tree < orange]

orangewood (ör´inj wud') •n. the wood of the orange tree, used as in carving •adj. of orangewood

orangutan (ou ræŋ´u: tæn'; ö ræŋ´-, э-; -ræŋ´э-) •n. a great ape (Pongo pygmaeus) with shaggy, reddish-brown hair, very long arms, small ears, and a hairless face: it is smaller than the gorilla and is found only in the swampy, coastal jungles of Borneo and Sumatra: also o·rang´ou·tang' (-tæŋ') [Malay oran utan, lit., man of the forest < oran, man + utan, forest, term for savage tribes: first applied to the ape by Europeans]

orangy or orangey (ör´in ji:, är´-) •adj. 1 resembling an orange in taste or smell 2 somewhat orange in color {an orangy pink}

orate (ou reit´, ö-; also our´eit', ör´-) o·rat´ed, o·rat´ing •vi. to make an oration; speak in a pompous or bombastic manner: a humorously derogatory term [back-form. < fol.]

oration (ou rei´shэn, ö rei´-) •n. a formal public speech, esp. one given at a ceremony SYN. SPEECH [ME oracion < L oratio < orare, to speak < IE base *ōr-, to speak, call > Gr ara, prayer]

orator (ör´эt эr, är´-) •n. 1 a person who delivers an oration 2 an eloquent public speaker [ME oratour < OFr orateur < L orator]

Oratorian (ör'э tör´i: эn) •n. a member of an Oratory

oratorical (ör'э tör´i kэl, är'-) •adj. 1 of or characteristic of orators or oratory 2 given to oratory or'a·tor´i·cal·ly •adv.

oratorio (ör'э tör´i: ou', är'-) pl. -os' •n. a long, dramatic musical composition, usually on a religious theme, consisting of arias, recitatives, choruses, etc. sung to orchestral accompaniment but without stage action, scenery, or costumes [It, lit., small chapel (< LL(Ec) oratorium: see ORATORY, sense 2): from the performance of such compositions at the Oratory of Saint Philip Neri in Rome]

oratory (ör´э tör'i:, är´-) pl. -ries •n. 1 the art of an orator; skill or eloquence in public speaking 2 a small chapel, esp. one for private prayer [ME oratorie < LL(Ec) oratorium, place of prayer < L oratorius, of an orator (in Eccles. use, of praying) < orator] 3 [O-] R.C.Ch. a religious society of secular priests, esp. that founded by Saint Philip Neri in 1564 [ME oratorie < L oratoria]

orb (örb) •n. 1 a sphere, or globe 2 a) any of the celestial spheres, as the sun, moon, etc. b) [Obs.] the earth c) the orbit of a planet 3 [Old Poet.] the eye or eyeball 4 a small globe with a cross on top, as a symbol of royal power 5 [Archaic] a) a sphere of activity; province b) rank; status 6 [Archaic] a collective body; organized whole 7 [Rare] anything circular in form; circle 8 Astrol. the sphere of influence of a planet, star, or house •vt. 1 to form into a sphere or circle 2 [Old Poet.] to enclose or encircle •vi. 1 [Rare] to move in an orbit 2 [Old Poet.] to take on the shape of an orb orbed •adj. orb´y •adj. [L orbis, a circle]

orbicular (ör bik´yu: lэr, -yэ-) •adj. 1 in the form of an orb; spherical or circular 2 Bot. round and flat, as some leaves: see LEAF, illus. Also or·bic´u·late (-lit, -leit') or·bic´u·lat'ed (-leit'id) or or·bic'u·lar´i·ty (-lær´э ti:) •n. or·bic´u·lar·ly •adv. [ME orbiculer < LL orbicularis < L orbiculus, dim. of orbis, a circle]

orbit (ör´bit) •n. 1 the bony cavity containing the eye; eye socket 2 [L orbita] a) the actual or imaginary path taken by a celestial body during its periodic revolution around another body b) the path taken by an artificial satellite or spacecraft around a celestial body3 the range of one's experience or activity; ordinary course of life 4 Zool. the skin around the eye of a bird •vi. to move in an orbit or circle •vt. 1 to put (a satellite or spacecraft) into an orbit in space 2 to move in an orbit around or´bit·al •adj. [MFr orbite < ML orbita < L, path, track < orbis, a circle, wheel]

orbital index the ratio of the greatest height of the orbital cavity to its greatest breadth, times 100

orbiter (ör´bit эr) •n. 1 one that moves in an orbit Æ 2 a spacecraft or artificial satellite designed to orbit a planet or other celestial body

ORC Officers' Reserve Corps orc (örk) •n. a killer whale or other cetacean identified by early writers as a sea monster [Fr orque < L orca, kind of whale, altered (infl. by orca, a large tub) < Gr oruga, acc. of oryx, a large fish]

orcein (ör´si: in) •n. a brownish-red, crystalline dye, C28H24N2O7, the main coloring matter of orchil, obtained from lichens or by treating orcinol with ammonia, and used as a biological stain, reagent, etc. [ORC(IN) + -e- + -IN¹]

orch orchestra

orchard (ör´chэrd) •n. 1 an area of land devoted to the cultivation of fruit trees or nut trees 2 such a stand of trees [ME < OE ortgeard < VL *orto, for L hortus, a garden (see HORTICULTURE) + OE geard, YARD²]

orchardist (-ist) •n. a person skilled or engaged in the cultivation of orchards: also or´chard·man (-mэn), pl. -men (-mэn)

orchestra (ör´kis trэ; also ör´kes'-) •n. 1 in ancient Greek theaters, the semicircular space in front of the stage, used by the chorus 2 in modern theaters, the space in front of and below the stage, where the musicians sit: in full orchestra pit Æ 3 a) the section of seats on the main floor of a theater, esp. the front section b) the main floor of a theater 4 a) a usually large group of musicians playing together; often, specif., SYMPHONY ORCHESTRA b) the instruments of such a group [L < Gr orchēstra < orcheisthai, to dance < IE base *ergh-, extension of base *er-, swift movement, a raising > Sans *rghāyati, (he) rages, Ger arg, bad]

orchestral (ör kes´trэl) •adj. of, for, by, or like an orchestra or·ches´tral·ly •adv.

orchestrate (ör´kis treit') -trat'ed, -trat'ing •vt., vi. 1 to compose or arrange (music) for an orchestra 2 to furnish (a ballet, etc.) with an orchestral score 3 to coordinate or arrange so as to achieve a desired result efficiently {orchestrate our efforts} or'ches·tra´tion •n. or´ches·tra'tor or or´ches·trat'er •n.

orchestrion (ör kes´tri: эn, -än') •n. a large, mechanical music box, somewhat like a barrel organ, that produces an effect imitative of that of an orchestra

orchi- (ör´ki) combining form ORCHIDO- (sense 1) {orchiectomy}

orchid (ör´kid) •n. 1 a perennial plant of the orchid family, that grows in the ground or as an epiphyte and is characterized by waxy pollen masses, minute seeds, and bilaterally symmetrical flowers with three petals, one of which is lip-shaped with many distinctive forms 2 the flower of such a plant; esp., any of the brightly colored tropical varieties cultivated for wear as a corsage 3 a light bluish red, or pale purple •adj. 1 of this color 2 designating a worldwide family (Orchidaceae, order Orchidales) of monocotyledonous plants [< ModL Orchideae: so named (1751) by LINNAEUS < *orchid-, mistaken as stem of L orchis: see ORCHIS]

orchido- (ör´ki dou, -dэ) combining form 1 testicle {orchidotomy} 2 orchid {orchidology} Also, before a vowel, orchid- [< *orchidos, mistaken as gen. of Gr orchis, testicle: see ORCHIS]

orchidology (ör'ki däl´э ji:) •n. the branch of horticulture dealing with orchids [prec. + -LOGY]

orchidotomy (ör'ki dät´э mi:) pl. -mies •n. the surgical incision of a testicle [ORCHIDO- + -TOMY]

orchiectomy (ör'ki: ek´tэ mi:) pl. -mies •n. the surgical removal of one or both testicles; castration [ORCHI- + -ECTOMY]

orchil (ör´kil, -chil) •n. 1 any of a number of lichens (genera Roccella, Dendrographa, and Lecanora) yielding purple dyes 2 any of these, including litmus

orchis (ör´kis) •n. an orchid; specif., any of a genus (Orchis) with small purplish or white flowers growing in spikes [ModL < L, orchid < Gr, orchid, lit., testicle (< IE base *orGhi- > Lith aržùs, lustful): from the shape of the roots]

orcinol (ör´sэ nöl', -noul') •n. a colorless, crystalline compound, C6H3·CH3(OH)2, that becomes red in air, obtained from aloes, lichens, etc. and used as a medicine, in dyes, etc.: also or´cin (-sin) [< It orcello, ARCHIL + -IN¹ + -OL¹]

Orcus (ör´kэs) Rom. Myth. 1 the lower world; Hades 2 Pluto, or Dis

ord 1 order 2 ordinal 3 ordinance 4 ordinary 5 ordnance

ordain (ör dein´) •vt. 1 orig., to put in order; arrange; prepare 2 a) to decree; order; establish; enact b) to predetermine; predestine 3 to invest with the functions or office of a minister, priest, or rabbi •vi. to command; decree or·dain´er •n. or·dain´ment •n. [ME ordeinen < OFr ordener < L ordinare, to arrange (in LL(Ec), to ordain as a priest) < L ordo, ORDER]

ordeal (ör di:l´, ör´di:l') •n. 1 an ancient method of trial in which the accused was exposed to physical dangers, from which he or she was supposed to be divinely protected if innocent 2 any difficult, painful, or trying experience; severe trial [ME ordal < OE, akin to Ger urteil, judgment < WGmc *uzdailjo-, what is dealt out < *uzdailjan, to deal out, allot, adjudge < *uz-, out + *dailjan < *dails, a part, share]

order (ör´dэr) •n. 1 social position; rank in the community 2 a state of peace and serenity; observance of the law; orderly conduct 3 the sequence or arrangement of things or events; series; succession 4 a fixed or definite plan; system; law of arrangement 5 a group or class of persons set off from others by some trait or quality 6 a) a group of persons constituting an association formed for some special purpose {the Order of Knights Templars} b) a community of monks, nuns, etc. following a rule {the Benedictine order} 7 a) a group of persons distinguished by having received a certain award or citation, as for outstanding service to a state {the Order of the Garter} b) the insignia of such a group 8 a state or condition in which everything is in its right place and functioning properly 9 condition or state in general {not in working order} 10 a command, direction, or instruction, usually backed by authority 11 a distinctive group; class; kind; sort {sentiments of a high order} 12 an established method or system, as of conduct or action in meetings, worship, court, etc. 13 a) a request or commission to make or supply something {an order for merchandise or services} b) the goods so made or supplied {to deliver a grocery order} Æ c) a single portion of some food, as served in a restaurant {an order of cole slaw} 14 Archit. a) any of several classical styles of structure, determined chiefly by the type of column and entablature (see DORIC, IONIC, CORINTHIAN) b) a style of building 15 Biol. a classification of a group of related plants or animals ranking above a family and below a class 16 Finance written instructions to pay money or surrender property 17 Gram. the arrangement or sequence of elements within a grammatical unit 18 Law a direction or command of a court, judge, public body, etc. 19 Math. a) a whole number describing the degree or stage of complexity of an algebraic expression b) an established sequence of numbers, letters, events, units, etc. c) the number of elements in a given group d) the number of rows or columns in a determinant or matrix 20 Theol. a) any of the nine ranks or grades of angels b) any rank or grade in the Christian clergy c) [usually pl.] the position of ordained minister, priest, etc. d) [usually pl.] ordination, as of a minister or priest e) HOLY ORDERS •vt. 1 to put or keep in order; organize; arrange 2 a) to instruct to do something; give an order to; command b) to command (someone) to go to or from a specified place {to order him out of the house} 3 to request or direct (something to be supplied) {to order merchandise} 4 [Archaic] Eccles. to ordain (a priest, etc.) •vi. 1 to give a command 2 to request that something be supplied SYN. COMMAND by order of according to the command of call to order to request to be quiet, as to start (a meeting) in (or out of) order 1 in (or not in) proper sequence or position 2 in (or not in) good condition 3 in (or not in) accordance with the rules, as of parliamentary procedure Æ 4 being (or not being) suitable to the occasion in order that so that; to the end that in order to for the purpose of; as a means to; to in short order without delay; quickly on order ordered, or requested, but not yet supplied on the order of 1 somewhat resembling; similar to 2 approximately; roughly order about to treat in a domineering manner: also order around Æ tall order [Colloq.] a difficult task or requirement to order in accordance with the buyer's specifications or´der·er •n. [OFr ordre < L ordo (gen. ordinis), straight row, regular series, akin to ordiri, to lay the warp, hence begin, set in order, prob. < IE base *ar-, to join, fit > ARM¹, ART¹]

order arms Mil. 1 to bring the rifle to an upright position with its butt on the ground beside the right foot, and remain at attention 2 a command to do this

Order of the Garter the highest order of British knighthood, instituted c. 1344 by Edward III

orderly (ör´dэr li:) •adj. 1 a) neat or tidy in arrangement; in good order b) arranged in, conforming to, or exhibiting some regular order; systematic 2 well-behaved; law-abiding; peaceful 3 having to do with the recording and transmission of military orders, records, etc. {the orderly room} •adv. in regular or proper order; methodically •n. pl. -lies 1 Mil. an enlisted person assigned to perform personal services for an officer or officers or to carry out a specific task {latrine orderly} 2 a male hospital attendant or´der·li·ness •n.

ordinal (örd´ªn эl; often örd´nэl) •adj. 1 expressing order or succession, specif. of a number in a series: see ORDINAL NUMBER 2 of an order of animals or plants •n. 1 ORDINAL NUMBER 2 [often O-] Eccles. a book of prescribed forms or ceremonies [ME ordynal, conforming to order < LL ordinalis < L ordo, ORDER]

ordinal number any number used to indicate order (e.g., second, ninth, 25th) in a particular series: distinguished from CARDINAL NUMBER

ordinance (örd´ªn эns; often örd´nэns) •n. 1 a direction or command of an authoritative nature 2 that which is held to be a decree of fate or of a deity 3 an established or prescribed practice or usage, esp. a religious rite Æ 4 a governmental, now esp. municipal, statute or regulation SYN. LAW [OFr ordenance < ordener: see ORDAIN]

ordinand (örd´ªn ænd') •n. a candidate for ordination [LL(Ec) ordinandus, ger. of ordinare, ORDAIN]

ordinarily (örd´ªn er'э li:, örd'ªn er´-) •adv. 1 usually; as a rule 2 in an ordinary manner or to an ordinary degree

ordinary (örd´ªn er'i:) pl. -nar'ies •n. 1 a) an official having jurisdiction within a specified area by right of the office he or she holds; esp., a bishop having such jurisdiction within his own diocese Æ b) in some States, a judge of probate 2 [Brit.] a) a set meal served regularly at the same price b) an inn, tavern, etc. where such meals are served 3 an early type of bicycle with one large wheel, and a smaller one behind 4 [often O-] Eccles. a) the form to be followed in a service b) the parts of the Mass that are fixed or relatively unvarying; common 5 Heraldry any one of the basic heraldic devices, as bend, fess, etc. •adj. [ME ordinarie < L ordinarius] 1 customary; usual; regular; normal 2 a) familiar; unexceptional; common; average b) relatively poor or inferior; below average 3 having immediate, not delegated, jurisdiction, as a judge SYN. COMMON out of the ordinary unusual; extraordinary or'di·nar´i·ness •n. [OFr & ML: OFr ordinarie < ML(Ec) ordinarius < L, an overseer, orig., orderly, regular < ordo, ORDER]

ordinary seaman a merchant seaman of less experience than, and ranking below, an able-bodied seaman

ordinate (örd´ªn it, -eit') •n. Math. the vertical Cartesian coordinate on a plane, measured from the x-axis along a line parallel with the y-axis to point P: see CARTESIAN COORDINATES, illus. [< ModL (linea) ordinate (applicata), line applied in ordered manner]

ordination (örd'ªn ei´shэn) •n. 1 the act of ordaining 2 a being ordained, as to the religious ministry [ME ordinacioun < L ordinatio < ordinare: see ORDAIN]

ordnance (örd´nэns) •n. 1 cannon or artillery 2 all military weapons together with ammunition, combat vehicles, etc. and the equipment and supplies used in servicing these 3 military branch or unit that orders, stores, and supplies ordnance [contr. < ORDINANCE, in restricted meaning]

ordo (ör´dou) pl. -dos or -di·nes' (-dэ ni:z') •n. R.C.Ch. an annual calendar that gives directions for each day's Mass and Office [L, lit., ORDER]

ordonnance (örd´ªn эns; Fr ôř dô näñs´) •n. 1 the proper or orderly arrangement of parts, as in a painting, literary work, etc. 2 in France, an ordinance, law, or decree [Fr < OFr ordenance: see ORDINANCE]

Ordovician (ör'dэ vish´эn) •adj. designating or of the second period of the Paleozoic Era immediately following the Cambrian and preceding the Silurian, characterized by an abundance of invertebrate life of many different kinds the Ordovician the Ordovician Period or its rocks: see GEOLOGY, chart [< L Ordovices, ancient Celtic tribe in Wales]

ordure (ör´jэr, -dyur) •n. dung; filth; manure; excrement [OFr < ord, filthy < L horridus, HORRID]

Ordzhonikidze (ôř'jô ni ki:d´ze) old name of VLADIKAVKAZ

ore (ör) •n. 1 any natural combination of minerals, esp. one from which a metal or metals can be profitably extracted 2 a natural substance from which a nonmetallic material, such as sulfur, can be extracted [ME or < OE ar, brass, copper (< IE base *ayos, metal, copper, bronze, iron > Sans áyas, metal, L aes, copper) identified with ora, unworked metal (akin to ON aurr, ferrous sand, gravel)]

öre (ö´řэ) pl. ö´re •n. a monetary unit of Sweden, equal to ¹/100 of a krona [Swed < ON aurar, a unit of weight, coin < L aureus, a gold coin, orig. adj., golden < aurum, gold: see EAST]

øre (ö´řэ) pl. ø´re •n. a monetary unit equal to ¹/100 of a Danish krone or a Norwegian krone [Dan & Norw < ON aurar: see ÖRE]

oread (ou´ri: æd') •n. Gr. & Rom. Myth. a mountain nymph [< L oreas (gen. oreadis) < Gr oreias (gen. oreiados) < oros, mountain: see ORIENT]

Örebro (ö'řэ břu:´) city in SC Sweden: pop. 118,000

Oreg Oregon

oregano (ö reg´э nou, э-) •n. any of a number of plants (esp. Origanum vulgare) of the mint family, the fragrant leaves of which are used for seasoning [Sp orégano < L origanum < Gr origanon]

Oregon (ör´i gэn, är´-; also, but not locally, -gän') NW coastal State of the U.S.: admitted, 1859; 96,981 sq. mi. (251,181 sq. km); pop. 2,842,000; cap. Salem: abbrev. OR or Oreg Or'e·go´ni·an (-gou´ni: эn) •adj., n. [prob. < AmInd ouragan (lit., birch-bark dish), native name of the COLUMBIA (River)]

Oregon fir DOUGLAS FIR: also Oregon pine

Oregon grape MAHONIA

Oregon myrtle CALIFORNIA LAUREL

Oregon Trail former route extending from the Missouri River in Mo., northwest to the Columbia River in Oreg., much used by westward migrants (c. 1840-60): c. 2,000 mi. (3,218 km)

Orel (ö rel´, ör yöl´) city in W European Russia, on the Oka: pop. 328,000

Orem (ör´эm) city in NC Utah: pop. 68,000 [after W. C. Orem (died 1951), pres. of a former interurban railroad in the area]

Orenburg (ôř'yэn buřkh) city in SE European Russia: pop. 519,000

Orestes (ou res´ti:z') Gr. Myth. son of Agamemnon and Clytemnestra, who, with the aid of his sister Electra, avenges the murder of his father by killing his mother and her lover Aegisthus [L < Gr Orestēs < oros, mountain: see ORIENT]

Öresund (Swed ö'řэ sûnd´) strait between Sweden and the Danish island of Zealand: c. 80 mi. (129 km) long: Dan. sp. Ø·re·sund (Dan, -sun´)

Orff (ôrf), Carl 1895-1982; Ger. composer

org 1 organic 2 organization 3 organized

organ (ör´gэn) •n. 1 a) a large wind instrument consisting of various sets of pipes which, as they are opened by corresponding keys on one or more keyboards, allow passage to a column of compressed air that causes sound by vibration b) any of several musical instruments producing similar or somewhat similar sounds (cf. ELECTRONIC ORGAN, REED ORGAN, BARREL ORGAN) c) [Archaic] any musical instrument; esp., a wind instrument 2 in animals and plants, a part composed of specialized tissues and adapted to the performance of a specific function or functions 3 a means or instrument for the performance of some action {an organ of local government} 4 a means of communicating ideas or opinions, as a periodical [ME organe < OE organa & OFr organe, both < L organum, tool, implement (in LL(Ec), a church organ) < Gr organon, an implement, engine < ergon, WORK]

organ grinder a person who plays a barrel organ in the streets

organdy or organdie (ör´gэn di:) pl. -dies •n. a very sheer, crisp cotton fabric used for dresses, curtains, etc. [Fr organdi < ?]

organelle (ör'gэ nel´) •n. a discrete structure within a cell, as a chloroplast or centriole, characterized by having specialized functions, a usually distinctive chemical composition, and an identifying molecular structure: often found in large numbers in a particular cell [Ger < ModL organella < L organum (< Gr organon: see ORGAN) + -ella, fem. of -ellus, dim. suffix]

organic (ör gæn´ik) •adj. 1 of or having to do with a bodily organ 2 of or involving the basic makeup of a thing; inherent; inborn; constitutional 3 made up of systematically interrelated parts; organized 4 a) designating or of any chemical compound containing carbon: some of the simple compounds of carbon, as carbon dioxide, are frequently classified as inorganic compounds b) designating or of the branch of chemistry dealing with carbon compounds 5 of, having the characteristics of, or derived from living organisms Æ 6 grown with only animal or vegetable fertilizers, as manure, bone meal, compost, etc. Æ 7 Law designating or of the fundamental, or constitutional, law of a state 8 Med. producing or involving alteration in the structure of an organ {an organic disorder}: cf. FUNCTIONAL (sense 3) or·gan´i·cal·ly •adv. [L organicus < Gr organikos]

organicism (-э siz'эm) •n. 1 HOLISM 2 the theory that living processes are a function of the entire, coordinated, autonomous system of an organism, rather than of any of its parts or·gan´i·cist •n., adj.

organism (ör´gэ niz'эm) •n. 1 any individual animal or plant having diverse organs and parts that function together as a whole to maintain life and its activities 2 anything resembling a living thing in its complexity of structure or functions or'gan·is´mic or or'gan·is´mal •adj. or'gan·is´mi·cal·ly •adv.

organist (ör´gэn ist) •n. an organ player [< MFr organiste or ML organista]

organization (ör'gэ ni zei´shэn, -nai-) •n. 1 an organizing or being organized 2 the manner of being organized; organic structure 3 [Rare] ORGANISM 4 any unified, consolidated group of elements; systematized whole; esp., a) a body of persons organized for some specific purpose, as a club, union, or society b) the administrative personnel or executive structure of a business c) all the functionaries, committees, etc. of a political party or'gan·i·za´tion·al •adj. or'gan·i·za´tion·al·ly •adv. [ME organizacion < ML organizatio]

organization man an employee, esp. of a large corporation, who has adapted so completely to what is expected in attitudes, ideas, behavior, etc. by the corporation as to have lost a sense of personal identity or independence

organize (ör´gэ naiz') -ized', -iz'ing •vt. 1 to provide with an organic structure; esp., a) to arrange in an orderly way {to organize files} b) to make into a whole with unified and coherent relationships {to organize an essay} c) to make plans or arrange for {to organize a campaign} 2 to bring into being; establish {to organize a corporation} 3 to persuade to join in some common cause or some organization; specif., a) to enlist in, or cause to form, a labor union Æ b) to enlist the employees of (an industry, business, etc.) in a labor union 4 [Colloq.] to set (oneself) into an orderly state of mind •vi. 1 to become organized Æ 2 to join in some common cause or form some organization, esp. a labor union or´gan·iz'a·ble •adj. [ME organyzen < ML organizare < L organum: see ORGAN]

organizer (-эr) •n. 1 a) a person who organizes Æ b) a labor-union official whose work is enlisting new members 2 Embryology any portion of a developing embryo, or any substance produced by it, capable of inducing differentiation in other portions

organo- (ör´gэ nou, -nэ; ör gæn´ou, -э) combining form 1 organ {organography} 2 organic {organophosphate} [< Gr organon, ORGAN]

organogenesis (ör'gэ nou'jen´э sis; ör gæn'ou-) •n. Biol. the origin and development of organs or'ga·no'ge·net´ic (-jэ net´ik) •adj. [ModL: see ORGANO- & -GENESIS]

organography (ör'gэ näg´rэ fi:) •n. Biol. the descriptive study of the organs of animals and plants, esp. the outer parts of plants or'ga·no'graph´ic (-nou'græf´ik) •adj. [ORGANO- + -GRAPHY]

organoleptic (ör´gэ nou'lep´tik; ör gæn'ou-) •adj. 1 affecting or involving an organ, esp. a sense organ 2 responsive to sensory stimuli [Fr organoleptique < Gr organon, ORGAN + lēptikos, disposed to accept < lēptos, verbal of lambainein, to seize: see LEMMA¹]

organology (ör'gэ näl´э ji:) •n. that branch of science dealing with the form, structure, development, and functions of plant or animal organs or'ga·no'log´ic (-nэ läj´ik) or or'ga·no'log´i·cal •adj. or'ga·nol´o·gist •n. [ORGANO- + -LOGY]

organometallic (ör'gэ nou'mэ tæl´ik; ör gæn'ou-) •adj. Chem. designating or of a compound containing carbon and a metal or nonmetal, specif. one in which the metal or nonmetal atom is firmly attached to one or more carbon atoms [ORGANO- + METALLIC]

organon (ör´gэ nän') pl. -na (-nэ) •n.or -nons' a means of acquiring knowledge; specif., a system of principles for use in philosophical or scientific inquiry [Gr: see ORGAN]

organophosphate (ör'gэ nou'fäs´feit'; ör gæn'ou-) •n. any organic compound containing phosphorus, specif. one used as an insecticide, as malathion [ORGANO- + PHOSPHATE]

organophosphorus (ör'gэ nou' fäs´fэ rэs, ör gæn'ou-) •adj. of an organic compound containing phosphorus

organosol (ör gæ´nэ säl') •n. a colloid consisting of a solid within an organic liquid: see PLASTISOL

organotherapy (ör'gэ nou'θer´э pi:; ör gæn'ou-) •n. the treatment of disease with extracts of animal organs, as of the glands of internal secretion [ORGANO- + THERAPY]

organotropic (-träp´ik) •adj. 1 designating or of a substance or virus that travels predominantly to a specific organ 2 having an affinity for a particular body organ or tissue [ORGANO- + -TROPIC]

organum (ör´gэ nэm) pl. -nums or -na (-nэ) •n. 1 ORGANON 2 Music a) an early type of polyphony based on plainsong, in which the voices are separated by an interval of a fourth, fifth, or octave b) a composition in this style [L: see ORGAN]

organza (ör gæn´zэ) •n. a thin, stiff fabric of rayon, silk, etc., used for bridal gowns, as underlining for sheer fabrics, etc. [< ? fol.]

organzine (ör´ gэn zi:n') •n. 1 a strong raw-silk thread made of twisted strands 2 a fabric made of such threads [Fr organsin < It organzino, prob. after Urganğ, name of a town in Russian TURKESTAN, famous as a silk market in medieval times]

orgasm (ör´gæz'эm) •n. a frenzy; great excitement; esp., the climax of sexual excitement, as in intercourse, normally accompanied in the male by ejaculation or·gas´mic (-gæz´mik) or or·gas´tic (-gæs´tik) •adj. [Fr orgasme < Gr orgasmos < organ, to swell with moisture, lust < IE base *werg-, to swell with sap or anger > Sans ūrjā, violence, vigor, sap]

orgeat (ör´zhæt', -jæt') •n. a syrup or beverage, orig. made from barley, flavored with almonds and orange flowers [Fr < Prov orjat < orge, barley < L hordeum < IE base *Ghrzd, barley > Ger gerste]

orgiastic (ör'ji: æs´tik) •adj. having to do with or resembling an orgy [Gr orgiastikos < orgiastēs, one who celebrates orgies < orgiazein, to celebrate orgies: see ORGY]

orgone (ör´goun') •n. a postulated energy permeating the universe, the personal supply of which an individual suffering from various emotional or physical ills can allegedly replenish by sitting in a small special cabinet (orgone box) in which this energy is supposed to accumulate [coined by W. Reich (1897-1957), Austrian psychiatrist in the U.S., prob. < ORG(ASM) + -one, as in OZONE]

orgy (ör´ji:) pl. -gies •n. 1 [usually pl.] in ancient Greece and Rome, feasting and wild celebration in worship of certain gods, esp. Dionysus 2 any wild merrymaking in a group, esp. with sexual activity 3 unrestrained indulgence in any activity [earlier chiefly in pl. < Fr orgies < L orgia, pl. < Gr, pl, secret rites, akin to ergon, WORK]

oribi (ör´э bi:) •n. an African pygmy antelope (0urebia ourebia), having a long tuft of hair growing from each knee and slender, straight horns [Afrik < Nama arab]

oriel (our´i: эl, ör´-) •n. a large window built out from a wall and resting on a bracket or a corbel; bay window [OFr oriol < ML oriolum, porch, gallery]

orient (for n. & adj. ör´i: эnt, our´-; for v., -ent', -эnt) •n. 1 [Old Poet.] the east 2 a) the quality that determines a pearl's value; luster b) a pearl of high quality •adj. [L oriens, direction of the rising sun, prp. of oriri, to arise < IE base *er-, to set in motion, elevate > RISE, RUN, Gr oros, mountain] 1 brilliant; shining; precious: orig. of pearls, now more general 2 [Old Poet.] a) eastern; oriental b) rising, as the sun •vt. [Fr orienter < the adj.] 1 to arrange with reference to the east; esp., to build (a church) with the chief altar at the eastern end 2 to set (a map or chart) in agreement with the points of the compass 3 to adjust with relation to facts or principles; correct 4 to adjust or adapt to, or acquaint with, a particular situation [O-] the East, or Asia; esp., the Far East [OFr < L oriens: see the adj.]

oriental (ör'i: ent´ªl, our'-) •adj. 1 [Old Poet.] eastern 2 being corundum of gemstone quality, but resembling another gem {oriental topaz} 3 [O-] of the Orient, its people, or their culture; Eastern 4 [O-] designating or of the biogeographic realm that includes SE Asia south of the Himalayas, the Philippines, Sumatra, Java, Borneo, and other associated islands •n. [usually O-] a native of the Orient or a member of a people native to that region [ME orientale < OFr oriental < L orientalis]

Oriental poppy a perennial poppy (Papaver orientale), cultivated for its large red, pink, or white flowers

Oriental rug any of various kinds of carpets made in the Orient, hand-woven in one piece, usually with intricate, colorful designs: also Oriental carpet

Oriental shorthair any of a breed of domestic cat, similar to the Siamese but with greenish eyes and often a coat of a solid color

Orientalism (-iz'эm) •n. 1 any trait, quality, mannerism, etc. usually associated with people of the East 2 study of Eastern culture O'ri·en´tal·ist •n. [prec. + -ISM]

Orientalize (-aiz') -ized', -iz'ing •vt., vi. to make or become Oriental in character, culture, customs, etc.

orientate (ör´i: en teit', our´-; also ör'i: en´-, our'-) -tat'ed, -tat'ing •vt. ORIENT •vi. 1 to face east, or in any specified direction 2 to adjust to a situation [ORIENT + -ATE¹, by assoc. with Fr orienter]

orientation (ör'i: en tei´shэn, our'-) •n. 1 an orienting or being oriented 2 a) position with relation to the points of the compass b) the planning of church architecture so that the altar is in the east end 3 familiarization with and adaptation to a situation or environment; specif., a) Psychol. awareness of one's environment as to time, space, objects, and persons b) a period or process of introduction and adjustment 4 Biol. the position or change of position of an organism or part under a stimulus, such as gravity, light, etc. 5 Chem. a) the position and arrangement of atoms or radicals in a molecule b) the ordering of molecules, crystals, etc. so that the axes point in a particular direction

orienteering (ör'i: en tir´iŋ, our'-) •n. a timed cross-country competition in which runners follow a course, using compass and map [< Swed orientering, lit., orientation]

orifice (ör´э fis, är´-) •n. a mouth or aperture of a tube, cavity, etc.; opening or'i·fi´cial (-fish´эl) •adj. [Fr < LL orificium < L os (gen. oris), a mouth (see ORAL) + -ficere < facere, to make, DO¹]

oriflamme (ör´i flæm') •n. 1 the ancient royal standard of France, a red silk banner with flame-shaped streamers 2 any battle standard 3 any symbol of courage or devotion [Fr < OFr orieflambe < L aurea flamma < aurum, gold (see EAST) + flamma, FLAME]

orig 1 origin 2 original 3 originally

origami (ör'э gä´mi:, our'-) •n. 1 a traditional Japanese art of folding paper to form flowers, animal figures, etc. 2 an object so made [Jpn]

Origen (ör´i jэn, är´-; -jen') (L. name Origenes Adamantius) c. A.D. 185-c. 254; Christian theologian & scholar, born in Alexandria

origin (ör´э jin, är´-) •n. 1 a coming into existence or use; beginning 2 parentage; birth; lineage 3 that in which something has its beginning; source; root; cause 4 Anat. the less movable of the two points of attachment of a muscle, usually the end attached to the more rigid part of the skeleton 5 Math. a) in a system of Cartesian coordinates, the point at which the axes intersect; base point where the abscissa and ordinate equal zero b) any zero reference point from which measurement begins SYN.—origin is applied to that from which a person or thing has its very beginning [the origin of a word]; source is applied to the point or place from which something arises, comes, or develops [the sun is our source of energy]; beginning is the basic general term for a starting point or place [the beginning of a quarrel]; inception is specifically applied to the beginning of an undertaking, organization, etc. [Smith headed the business from its inception]; root suggests an origin so deep and basic as to be the ultimate cause from which something stems [to go to the root of the matter] [ME origyne < MFr origine < L origo (gen. originis) < oriri, to rise: see ORIENT]

original (э rij´i nэl) •adj. 1 having to do with an origin; first; earliest 2 never having occurred or existed before; fresh; new; novel 3 capable of or given to inventing or creating something new, or thinking or acting in an independent, individual, fresh way 4 coming from someone as the originator, maker, author, etc. 5 being that from which reproductions, copies, etc. have been made •n. [Fr < the adj.] 1 a pristine form or primary type that has given rise to varieties 2 an original work, as of art or literature, as distinguished from a reproduction, copy, etc. 3 the person or thing represented in a painting or the like 4 a) a person with an original and creative mind b) [Archaic] an eccentric person 5 [Archaic] an originator SYN. NEW [OFr < L originalis]

original sin Christian Theol. the sin of disobedience committed by Adam and Eve, traditionally viewed as transmitted in its essential guilt and consequent penalties from Adam as head of the human race to all unredeemed mankind

originality (э rij'i næl´э ti:) •n. 1 the quality or condition of being original 2 the ability to be original, inventive, or creative [Fr originalité]

originally (э rij´i nэl i:) •adv. 1 with reference to origin, or beginning 2 in the first place; initially 3 in an original, independent, or novel manner

originate (э rij´i neit') -nat'ed, -nat'ing •vt. to bring into being; esp., to create (something original); invent •vi. to come into being; begin; start SYN. RISE o·rig'i·na´tion •n. o·rig´i·na'tive •adj. o·rig´i·na'tor •n. [< ML originatus, pp. of originari, to begin < L origo: see ORIGIN]

orinasal (our'э nei´zэl, ör'-) •adj. Phonet. articulated with breath passing through the mouth and the nose at the same time, as some French vowels •n. an orinasal sound [< L os (gen. oris), a mouth (see ORAL) + NASAL]

O-ring (ou´riŋ') •n. a ring-shaped seal or washer of rubber, plastic, metal, etc., used to prevent leaks in parts connecting pipes, tubes, rocket sections, etc.

Orinoco (ör'э nou´kou) river in Venezuela, flowing from the Brazil border into the Atlantic: c. 1,700 mi. (2,736 km)

oriole (ör´i: oul', our´-) •n. 1 any of an Old World family (Oriolidae) of chiefly yellow-and-black passerine birds, including the golden oriole (Oriolus oriolus) 2 any of a genus (Icterus, family Icteridae) of American passerine birds, including the Baltimore oriole, that have bright plumage of orange, or yellow, and black, and build hanging nests [OFr oriol < ML aureolus < L, golden, dim. of aureus < aurum, gold: see EAST]

Orion (ou rai´эn, э-) 1 Gr. & Rom. Myth. a hunter whom Diana loves but accidentally kills 2 Astron. an equatorial constellation between Taurus and Lepus, containing the bright stars Rigel and Betelgeuse [ME < L < Gr Ōriōn]

orison (ör´i zэn, -sэn) •n. [Literary] a prayer [ME oreisun < OFr oreison < LL(Ec) oratio, a prayer < L, a speech: see ORATION]

Orissa (ou ris´э) state of E India, on the Bay of Bengal: 60,118 sq. mi. (155,707 sq. km); pop. 26,272,000; cap. Bhubaneswar

Orizaba (ô'ři: sä´bä) 1 volcanic mountain in SE Mexico, highest mountain in Mexico: 18,700 ft. (5,700 m) 2 city at the foot of this mountain, in Veracruz state: pop. 115,000

Orkney Islands (örk´ni:) group of islands north of Scotland, constituting a region of Scotland: 376 sq. mi. (974 sq. km); pop. 19,000 [< ON Orkneyjar, lit., seal islands < orkn, a seal + ey, ISLAND]

Orlando (ör læn´dou) city in central Fla.: pop. 165,000 (met. area 1,073,000) [after Orlando Reeves, a soldier killed there in an Indian attack] Orlando (ör læn´dou; also, for 2, It ôř län´dô) 1 a masculine name: see ROLAND 2 Vit·to·rio E·ma·nue·le (vi:t tô´řyô e'mä nwe´le) 1860-1952; It. statesman: premier of Italy (1917-19) [It]

orle (örl) •n. Heraldry the inner border on an escutcheon, following the outline of the edge of the shield [Fr < OFr ourle, urle, dim. < L ora, margin, border < os, mouth, edge: see ORAL]

Orléanais (ôř lei å ne´) historical region in NC France: chief city, Orléans

Orleanist (ör´li: эn ist) •n. a supporter of the house of Orléans' claim to the French throne through the Duke of Orléans, a younger brother of Louis XIV

Orléans (ôř lei äñ´; E ör´li: эnz) city in NC France, on the Loire: pop. 84,000 Orléans (ôř lei äñ´; E ör´li: эnz) 1 a branch of the house of Bourbon, one of whose members (Louis Philippe) ruled France, 1830-48 2 Louis Phi·lippe Jo·seph Duc d' (lwi:´ fi: li:p´ zhô zef´) 1747-93; Fr. revolutionist: guillotined: father of Louis Philippe

Orlon (ör´län') trademark for a synthetic acrylic fiber somewhat like nylon, or a fabric made from this fiber •n. [o-] this fiber or fabric [arbitrary coinage, after (NYL)ON]

orlop (ör´läp) •n. [Now Rare] the lowest deck of a ship with four or more decks [ME ouerlop < Du overloop < over, over + loopen, to run (see LEAP): so called because it covers the hold]

Ormazd (ör´mэzd, -mæzd') Zoroastrianism the supreme deity and creator of the world, or the spirit of good: cf. AHRIMAN: also sp. Or´muzd [Pers < OPers Auramazda < Avestan Ahuro-Mazdao, wise lord < ahura, a god (see OSCAR) + mazdah-, name of the highest god < IE *mendh-, to direct one's mind toward < base *men-, to think (> MIND) + *dhē-, to put (< DO¹)]

ormer (ör´mэr) •n. [Brit. dial.] term for ABALONE [Fr dial. (Channel Islands) < Fr ormier < L auris maris, ear of the sea (see EAR¹ & MARE²): from its shape]

ormolu (ör´mэ lu:') •n. 1 an imitation gold made of an alloy of copper and tin, used in making ornaments, moldings, cheap jewelry, etc. 2 imitation gold leaf [Fr or moulu, lit., ground gold < or (see OR³) + pp. of moudre < L molere, to grind: see MILL¹]

Ormuz (ör´mûz'), Strait of see HORMUZ, Strait of

ornament (for n., ör´nэ mэnt; for v., -ment') •n. 1 anything serving to adorn; decoration; embellishment; also, a desirable or needed adjunct 2 a person whose character or talent adds luster to the surroundings, society, etc. 3 an adorning or being adorned; ornamentation 4 mere external display 5 Music a tone or tones used to embellish a principal melodic tone •vt. to furnish with ornaments or be an ornament to; decorate; beautify SYN. ADORN or´na·ment'er •n. [OFr ornement < L ornamentum < ornare, to adorn (akin to ordinare: see ORDAIN)]

ornamental (ör'nэ ment´ªl) •adj. serving as or pertaining to an ornament; decorative •n. something ornamental; specif., a plant or shrub grown for its decorative effect or'na·men´tal·ly •adv.

ornamentation (ör'nэ men tei´shэn, -mэn-) •n. 1 an ornamenting or being ornamented 2 ornaments collectively; decoration

ornate (ör neit´) •adj. 1 heavily ornamented or adorned, often to excess 2 showy or flowery, as some literary styles or·nate´ly •adv. or·nate´ness •n. [ME < L ornatus, pp. of ornare: see ORNAMENT]

ornery (ör´nэr i:) •adj. [Chiefly Dial.] 1 having an ugly or mean disposition 2 obstinate Æ or´ner·i·ness •n. [altered < ORDINARY]

ornis (ör´nis) •n. AVIFAUNA [Ger < Gr ornis, bird: see ORNITHO-]

ornithic (ör niθ´ik) •adj. of or characteristic of birds [Gr ornithikos < ornis, bird: see ORNITHO-]

ornithine (ör´nэ θi:n', -θin) •n. a nonessential amino acid, NH2(CH2)3CH(NH2)COOH, found in animals as a product of urea formation from proteins and in the excrement of birds [< Gr ornis, bird (see ORNITHO-) + -INE³]

ornitho- (ör´nэ θou, -θэ) combining form bird or birds {ornithology}: also, before a vowel, ornith- [< Gr ornis (gen. ornithos), bird < IE base *er-, eagle, large bird > Goth ara]

ornithoid (ör´nэ θoid') •adj. like a bird in appearance or structure [< prec. + -OID]

ornithology (ör'nэ θäl´э ji:) •n. the branch of zoology dealing with birds or·ni·tho·log·i·cal (ör'ni θou läj´i kэl) •adj. or'ni·tho·log´i·cal·ly •adv. or'ni·thol´o·gist •n. [ModL ornithologia: see ORNITHO- & -LOGY]

ornithopod (ör´ni θou päd'; ör nai´θou-, -niθ´ou-) •n. any of a suborder (Ornithopoda, order Ornithischia) of plant-eating dinosaurs that walked upright on digitigrade hind feet [< ModL Ornithopoda: see ORNITHO- & -POD]

ornithopter (ör´nэ θäp'tэr) •n. an experimental type of aircraft designed to be propelled by the flapping of the wings [< ORNITHO- + Gr pteron, wing, FEATHER]

ornithorhynchus (ör'nэ θou'riŋ´kэs) •n. PLATYPUS [< ORNITHO- + Gr rhynchos, bill, snout < IE echoic base *srungh-, to snort]

ornithosis (ör'nэ θou´sis) •n. a virus disease, such as psittacosis, transmitted by birds [ModL < ORNITH(O)- + -OSIS]

oro- (ou´rou, -rэ; ör´ou, -э) combining form mountain {orography} [< Gr oros, mountain: see ORIENT]

orogeny (ou räj´э ni:) pl. -nies the formation of mountains through structural disturbance of the earth's crust, esp. by folding and faulting: also or·o·gen·e·sis (ör'ou jen´э sis) •n. or'o·gen´ic (-jen´ik) or or'o·ge·net´ic (-jэ net´ik) •adj. [prec. + -GENY]

orography (ou räg´rэ fi:) •n. the branch of physical geography dealing with mountains or·o·graph·ic (ör'ou græf´ik) or or'o·graph´i·cal •adj. [ORO- + -GRAPHY]

oroide (ou´rou aid', -id; ör´ou-) •n. an alloy, mainly of copper, tin, and zinc, resembling gold, used in cheap jewelry [< Fr oréide: see OR³ & -IDE]

orology (ou räl´э ji:) •n. the study of mountains or·o·log·i·cal (ör'ou läj´i kэl) •adj. [ORO- + -LOGY]

Oromo (ou rou´mou) •n. 1 pl. -mos or -mo a member of a group of peoples of S Ethiopia and neighboring regions 2 the Cushitic language of these peoples [self-designation]

Orontes (ou rän´ti:z) river in SW Asia, flowing from Lebanon through Syria & Turkey into the Mediterranean: c. 240 mi. (386 km)

orotund (ou´rou tûnd', -rэ-; ör´ou-, ör´э-) •adj. 1 clear, strong, and deep; resonant: said of the voice 2 bombastic or pompous: said of a style of speaking or writing o'ro·tun´di·ty (-tûn´dэ ti:) •n. [< L ore rotundo, lit., with a round mouth: see ORAL & ROTUND]

Orozco (ô řôs´kô), Jo·sé Cle·men·te (hô se´ kle men´te) 1883-1949; Mex. painter

orphan (ör´fэn) •n. a child whose father and mother are dead: sometimes applied to a child who has lost only one parent by death •adj. 1 being an orphan 2 of or for orphans {an orphan home} 3 of a product that is medically valuable but is not produced because it lacks a profitable market, as a drug for a rare disease •vt. to cause to become an orphan {orphaned by the war} or´phan·hood' •n. [LL(Ec) orphanus < Gr orphanos < IE base *orbho-, orphan > L orbus, bereft, Ger erbe, inheritance, arbeit, work, Czech robotnik, serf]

orphanage (ör´fэn ij) •n. 1 the condition of being an orphan 2 an institution that is a home for orphans

Orpheus (ör´fi: эs, -fyu:s') Gr. Myth. a poet-musician with magic musical powers who descends to the underworld and tries to lead his wife, Eurydice, back from the dead but fails because he breaks the injunction not to look back at her until they reach the upper world Or´phe·an •adj. [L < Gr]

Orphic (ör´fik) •adj. 1 of or characteristic of Orpheus or the mystic doctrines and rites in worship of Dionysus ascribed to him 2 [also o-] a) like the music attributed to Orpheus; entrancing b) mystic; occult; oracular [L Orphicus < Gr Orphikos]

Orphism (ör´fiz'эm) •n. the rites and religion ascribed to Orpheus as founder

orphrey (ör´fri:) •n. a richly embroidered decorative band, as on a chasuble [ME orferay, taken as sing. of orfreis, orphrey < OFr < ML aurifrigium < L aurum, gold (see EAST) + ML frisium, FRIEZE¹]

orpiment (ör´pi mэnt) •n. arsenic trisulfide, As2S3, having a lemon-yellow color and a resinous luster: it is used as a pigment [OFr < L auripigmentum, pigment of gold: see AURIC & PIGMENT]

orpine (ör´pin) •n. any of various plants (esp. genus Sedum) of the orpine family, with fleshy leaves and stems, and white, yellow, or purple flowers •adj. designating a family (Crassulaceae, order Rosales) of succulent, dicotyledonous plants, including the sempervivums and sedums [ME orpin < MFr < orpiment (see ORPIMENT): orig. used of a yellow-flowered plant]

Orpington (ör´piŋ tэn) •n. any of a breed of large, full-bodied chicken, often brownish yellow in color and with featherless legs, usually raised for its meat [after Orpington, village in KENT]

orrery (ör´эr i:) pl. -rer·ies •n. a mechanical apparatus which illustrates with balls of various sizes the relative motions and positions of the earth, moon, sun, etc. [after Charles Boyle, Earl of Orrery (1676-1731), for whom one was made]

orris (ör´is, är´-) •n. any of several European irises, esp. a white-flowered species (Iris florentina) whose rootstocks yield orrisroot [prob. altered < ME ireos < ML yreos < Gr ireos, made from iris < iris, IRIS]

orrisroot (-ru:t') •n. the rootstock of the orris: pulverized and used in perfumery, tooth powders, etc.

Orsk (ôřsk) city in SE European Russia, on the Ural River: pop. 266,000

Orson (ör´sэn) a masculine name [< Fr ourson, dim. of ours, a bear < L ursus]

ort (ört) •n. [Now Chiefly Dial.] a scrap or fragment of food left from a meal: usually used in pl. [LME ortus, pl., prob. < LowG]

Ortega y Gasset (ôř te´gä i: gä set´), Jo·sé (hô se´) 1883-1955; Sp. essayist & philosopher

Ortegal (ôř'te gäl´), Cape cape in NW Spain, extending into the Bay of Biscay

orthicon (ör´θi kän') •n. a television camera tube, an improved form of the iconoscope, in which the charges on a photosensitive plate are scanned by a low-velocity electron beam which is reflected and which delivers the signal current to an output electrode: also or'thi·con´o·scope' (-э skoup') [fol. + ICON(OSCOPE)]

ortho- (ör´θou, -θэ) combining form 1 straight, regular, upright {orthognathous} 2 at right angles, perpendicular {orthorhombic} 3 proper, correct, standard {orthography} 4 Chem. a) that acid (of a group containing the same nonmetallic element) which has the largest number of OH groups per atom of the nonmetal {orthophosphoric acid} b) characterized by substitutions in the 1, 2 position in the benzene ring: usually italicized and hyphenated in chemical names {ortho-aminobenzoic acid}: see PARA-¹ (sense 2b), META- (sense 6d) 5 Med. correction of deformities {orthopedics} Also (except for sense 4b), before a vowel, orth- [< Gr orthos, straight < IE base *werdh-, to grow, climb, high > Sans várdhati, (he) grows]

orthocephalic (ör'θou sэ fæl´ik) •adj. having a skull whose height is 70.1 to 75 percent of its length, from front to back: see CEPHALIC INDEX: also or'tho·ceph´a·lous (-sef´э lэs) or'tho·ceph´a·ly •n. [prec. + -CEPHALIC]

orthochromatic (-krou mæt´ik) •adj. designating or of photographic film that is sensitive to all colors except red and deep orange [ORTHO- + CHROMATIC]

orthoclase (ör´θou kleis', -kleiz'; -θэ-) •n. potassium feldspar, KAlSi3O8, a monoclinic mineral that is a common constituent of many granitic rocks [Ger orthoklas < Gr orthos (see ORTHO-) + klasis, fracture (< klan, to break: see CLASTIC), because of the 90° cleavage]

orthodontics (ör'θou dän´tiks, -θэ-) •n.pl. [with sing. v.] the branch of dentistry concerned with diagnosing, correcting, and preventing irregularities of the teeth and poor occlusion: also or'tho·don´ti·a (-dän´shэ, -shi: э) or'tho·don´tic •adj. or'tho·don´tist •n. [ModL: see ORTH(O)-, -ODONT, & -ICS]

orthodox (ör´θэ däks') •adj. 1 conforming to the usual beliefs or established doctrines, as in religion, politics, etc.; approved or conventional [orthodox ideas]; specif., a) conforming to the Christian faith as formulated in the early ecumenical creeds and confessions b) [O-] strictly conforming to the rites and traditions of Judaism, such as kashrut, the Sabbath, etc., as formulated by the Torah and Talmud 2 [O-] designating or of any of the churches comprised in the Eastern Orthodox Church [< Fr or LL: Fr orthodoxe < LL orthōdoxus < LGr(Ec) orthodoxos, orthodox (in religion) < Gr orthos (see ORTHO-) + doxa, opinion < dokein, to think: see DECENT]

Orthodox Eastern Church EASTERN ORTHODOX CHURCH

orthodoxy (ör´θэ däk'si:) pl. -dox'ies •n. 1 the quality or fact of being orthodox 2 an orthodox belief, doctrine, custom, etc. [Gr orthodoxia]

orthoepy (ör θou´э pi:; also ör´θou э pi:, -θou ep'i:) •n. 1 the study of pronunciation; phonology 2 the standard pronunciation of a language or·tho·ep·ic (ör'θou ep´ik) or or'tho·ep´i·cal •adj. or·tho´e·pist •n. [ModL orthoepia < Gr orthoepeia < orthos, right + epos, a word: see ORTHO- & EPIC]

orthogenesis (ör'θou jen´э sis) •n. 1 Biol. a now discredited theory that states that the progressive evolution of certain organisms in a restricted direction throughout successive generations is independent of outside influences and natural selection 2 Anthrop. the theory, no longer accepted, that every culture follows the same fixed course of evolution, uninfluenced by differing environmental factors or'tho·ge·net´ic (-jэ net´ik) •adj. [ModL: see ORTHO- & -GENESIS]

orthognathous (ör θäg´nэ θэs) •adj. having the jaws in line, with the lower jaw neither projecting nor receding: also or'thog·nath´ic (-θäg næθ´ik) or·thog´na·thism •n. [ORTHO- + -GNATHOUS]

orthogonal (ör θäg´э nэl) •adj. having to do with right angles; perpendicular; rectangular or·thog´o·nal·ly •adv. [Fr < orthogone, right-angled < L orthogonius < Gr orthogōnios: see ORTHO- & -GON]

orthograde (ör´θou greid') •adj. Zool. walking with the body upright [ORTHO- + -GRADE]

orthographic (ör'θou græf´ik, -θэ-) •adj. 1 of or characterized by orthography 2 Geom. of right angles and perpendicular lines; orthogonal Also or'tho·graph´i·cal or'tho·graph´i·cal·ly •adv.

orthographic projection Archit., Geom. a projection in which the projecting lines are perpendicular to the plane of projection

orthography (ör θäg´rэ fi:) pl. -phies •n. 1 spelling in accord with accepted usage 2 any style or method of spelling 3 spelling as a subject for study 4 ORTHOGRAPHIC PROJECTION or·thog´ra·pher •n. [ME ortografye < MFr ortographie < L orthographia < Gr: see ORTHO- & -GRAPHY]

orthokeratology (ör'θou ker'э täl´э ji:) •n. a branch of optometry that seeks to reduce certain refractive errors in the eye by altering the curvature of the cornea through the application of a series of graduated contact lenses over a period of time [ORTHO- + KERATO- + -LOGY]

orthomolecular (ör'θou mэ lek´yэ lэr) •adj. of or involving a regimen in which megavitamins, trace minerals, etc. are taken in an effort to improve the balance of nutrients in the body molecules [ORTHO- + MOLECULAR]

orthopedics or orthopaedics (ör'θou pi:´diks) •n.pl. [with sing. v.] the branch of medicine dealing with the treatment of deformities, diseases, and injuries of the bones, joints, muscles, etc. or'tho·pe´dic or or'tho·pae´dic •adj. or'tho·pe´dist or or'tho·pae´dist •n. [< Fr orthopédique, orthopedic < orthopédie < Gr orthos, straight (see ORTHO-) + paideia, training of children < pais (gen. paidos), child: see PEDO-¹]

orthophosphate (ör'θou fäs´feit') •n. 1 a salt of orthophosphoric acid containing the trivalent, negative radical PO4 2 an uncharged ester of this acid [ORTHO- + PHOSPHATE]

orthophosphoric acid (-fäs four´ik) a clear, colorless, syrupy liquid or a colorless, crystalline solid, H3PO4, produced from phosphorus or phosphate rock and used in the manufacture of fertilizers, textiles, etc. [ORTHO- + PHOSPHORIC]

orthopsychiatry (-sai kai´э tri:) •n. the study and treatment of disorders of behavior and personality, with emphasis on prevention through a clinical approach or'tho·psy'chi·at´ric (-sai'ki: æ´trik) •adj. or'tho·psy·chi´a·trist •n. [ORTHO- + PSYCHIATRY]

orthopter (ör θäp´tэr) •n. ORNITHOPTER

orthopteran (ör θäp´tэr эn) •n. any of a large order (Orthoptera) of mostly plant-eating insects, including crickets, grasshoppers, and katydids, having chewing mouthparts and narrow, hard forewings that cover membranous hind wings in most species, and undergoing gradual metamorphosis or·thop´ter·ous •adj. [< ModL Orthoptera < ORTHO- + Gr pteron, wing, FEATHER]

orthoptic (ör θäp´tik) •adj. correcting any deviations of the visual axis of the eye, esp. by exercises to strengthen the eye muscles [ORTH(O)- + OPTIC]

orthorhombic (ör'θou räm´bik) •adj. designating or of a system of crystallization characterized by three axes unequal in length and at right angles to one another [ORTHO- + RHOMBIC]

orthoscope (ör´θou skoup') •n. an instrument containing a layer of water which is held in contact with the eye, allowing an examination of the interior of the eye without the distortion due to corneal refraction [ORTHO- + -SCOPE]

orthoscopic (ör'θou skäp´ik) •adj. giving a true flat image without distortion [< ORTHO- + Gr skopein, to view (see SCOPE) + -IC]

orthostatic (-stæt´ik) •adj. of or caused by an upright position {orthostatic hypotension} [ORTHO- + STATIC]

orthostichy (ör θäs´ti ki:) pl. -chies •n. a vertical arrangement of leaves or flowers on a stem or·thos´ti·chous •adj. [< ORTHO- + Gr stichos, a row (see STILE²) + -Y³]

orthotics (ör θät´iks) •n.pl. [with sing. v.] the science of developing and fitting surgical devices designed to activate or supplement a weakened or atrophied limb or function or·thot´ic •adj. or·tho·tist (ör´θэ tist) •n. [ORTH(O)- + -OTIC + s]

orthotropic (ör'θou träp´ik) •adj. 1 designating or of a design for bridges in which the structural supporting units also form the deck, or road surface, thus reducing weight and cost of construction 2 Bot. designating, of, or showing vertical growth, as most main stems and roots [ORTHO- + -TROPIC]

orthotropism (ör θä´trэ piz'эm) •n. growth, or a tendency to grow, in a vertical direction or position [ORTHO- + -TROPISM]

orthotropous (ör θä´trэ pэs) •adj. Bot. growing straight: said of an ovule with its hilum and micropyle in a straight line [ORTHO- + -TROPOUS]

Ortles (ôřt´leis) range of the E Alps, in N Italy: highest peak (Ort´les), 12,792 ft. (3,900 m): Ger. name Ort·ler (ôřt´lэř)

ortolan (ör´tэ lэn) •n. an Old World bunting (Emberiza hortulana) prized as a choice food [Fr < Prov < It ortolana, gardener, ortolan < L hortulanus, dim. of hortus, a garden (see YARD²): from its frequenting gardens]

Oruro (ö rur´ou) city in W Bolivia: pop. 132,000

Orville (ör´vil) a masculine name [Fr; orig. place name]

Orwell (ör´wel, -wэl), George (pseud. of Eric Arthur Blair) 1903-50; Eng. writer Or·well´i·an •adj.

-ory (ör´i:, our´i:; эr i:) suffix 1 forming adjectives of, having the nature of {sensory, valedictory} [ME -orie < OFr -oire < L -orius, -oria, -orium] 2 forming nouns a place or thing for {crematory} [ME -orie < OFr -oire, -orie < L -orium]

oryx (our´iks, ör´-) pl. o´ryx·es •n.or o´ryx any of a genus (Oryx) of large African and Asian antelopes with long, straight horns, including the gemsbok [ModL < L, wild goat, gazelle < Gr, lit., pickax (< oryssein, to dig: for IE base see RUPTURE): from its pointed horns]

orzo (ör´tsou') •n. pasta in the form of grains of rice

Os Chem. symbol for osmium OS 1 Old Saxon 2 old series 3 Old Style 4 Ordinary Seaman 5 out of stock Also, for 2 & 5, os os (ous) pl. o·sar (ou´sär') •n. ESKER [Swed ås, ridge, pl. åsar < ON āss < IE base *omso-, shoulder > Gr ōmos, L umerus, shoulder]

os¹ (äs) pl. os´sa (-э) •n. a bone [L: see OSSIFY]

os² (äs) pl. o·ra (ou´rэ; our´э, ör´э) •n. a mouth; opening [L: see ORAL]

Osage (ou seij´, ou´seij') river in central Mo. & E Kans., flowing east into the Missouri: c. 500 mi. (804 km) [after prec.] Osage (ou seij´, ou´seij') •n. 1 pl. O·sag´es or O·sage´ a member of a tribe of Indians who migrated from the Ohio River Valley and now live in Oklahoma 2 their Siouan language [< Osage Wazhazhe]

Osage orange (ou´seij') 1 a small thorny tree (Maclura pomifera) of the mulberry family, with hard, yellow wood, native to the central U.S. and often used for hedges 2 its greenish-yellow, orange-shaped, inedible fruit

Osaka (ô´sä kä'; E ou´sä kä') seaport in S Honshu, Japan: pop. 2,648,000

OSB Order of St. Benedict

Osborn (äz´bэrn), Henry Fairfield 1857-1935; U.S. paleontologist & biologist

Osborne (äz´bэrn, -börn) 1 John (James) 1929- ; Eng. playwright 2 Thomas Mott (mät) 1859-1926; U.S. prison reformer

Oscan (äs´kэn) •n. 1 a member of an ancient people who lived in Campania, Italy 2 their Italic language •adj. of the Oscans or their language [< L Oscus, Oscan + -AN]

Oscar (äs´kэr) 1 a masculine name 2 Oscar II 1829-1907; king of Norway & Sweden (1872-1905), then of Sweden alone •n. [said to be so named from comment (He reminds me of my Uncle Oscar) made by an Academy official on first seeing the statuette] Æ 1 any of the statuettes awarded annually in the U.S. for achievements in motion pictures 2 [Colloq.] an Academy Award [OE Osgar < os, a god, akin to ON áss (< IE *ansu-, a spirit, demon > Avestan ahura) + gar, a spear]

Osceola (äs´i: ou´lэ) c. 1804-38; leader of the Seminole Indians

oscillate (äs´э leit') -lat'ed, -lat'ing •vi. 1 to swing or move regularly back and forth 2 to be indecisive in purpose or opinion; vacillate 3 Physics to vary regularly between maximum and minimum values, as an electric current •vt. to cause to oscillate SYN. SWING os´cil·la·to'ry (-lэ tör'i:) •adj. [< L oscillatus, pp. of oscillare, to swing < oscillum, a swing]

oscillation (äs'э lei´shэn) •n. 1 the act of oscillating 2 fluctuation; instability; variation 3 Physics a) repeated variation in the value of some physical quantity, as position or voltage b) a single instance or cycle of such a variation [L oscillatio]

oscillator (äs´э leit'эr) •n. 1 a person or thing that oscillates 2 Physics an apparatus, as an electric circuit, for establishing and maintaining oscillations

oscillogram (э sil´э græm', äs´э lou-) •n. a record obtained from an oscillograph [see -GRAM]

oscillograph (-græf') •n. an instrument for displaying or recording in the form of a curve the instantaneous values of rapidly varying electrical quantities os·cil'lo·graph´ic •adj. [< L oscilarre, to swing + -GRAPH]

oscilloscope (-skoup') •n. a type of oscillograph that visually displays an electrical wave on a fluorescent screen, as of a cathode-ray tube os·cil'lo·scop´ic (-skäp´ik) •adj. [< L oscillare, to swing + -SCOPE]

oscine (äs´in, -ain') •adj. designating or of the major suborder (Oscines) of passerine birds characterized by a highly developed syrinx, including most common perching birds •n. a bird of this suborder [< ModL Oscines, name of the group < L, pl. of oscen, bird whose notes were used in divining < obs-, var. of ob- (see OB-) + canere, to crow, sing (see CHANT, vi.)]

oscitancy (äs´э tэn si:) •n. drowsiness, dullness, apathy, etc. [< L oscitans, prp. of oscitare, to yawn < os, a mouth + citare, to move: see CITE]

Osco-Umbrian (äs´kou ûm´bri: эn) •n. a branch of the Italic subfamily of languages consisting of Oscan and Umbrian

osculant (äs´kyu: lэnt, -kyэ-) •adj. 1 Biol. intermediate; linking; shared: said of a characteristic common to two or more groups, genera, etc. 2 Zool. gripping or adhering together [L osculans, prp. of osculari: see OSCULATE]

oscular (äs´kyu: lэr, -kyэ-) •adj. 1 of the mouth or kissing 2 Zool. of an osculum [L osculum (see OSCULATE) + -AR]

osculate (äs´kyu: leit', -kyэ-) -lat'ed, -lat'ing •vt., vi. 1 to kiss: a pretentious or facetious usage 2 to touch closely os'cu·la´tion •n. os´cu·la·to'ry (-lэ tör'i:) •adj. [< L osculatus, pp. of osculari, to kiss < osculum, little mouth: see OSCULUM]

osculum (äs´kyu: lэm, -kyэ-) pl. -la (-lэ) •n. any of the openings of a sponge though which water passes out [L, dim. of os, a mouth: see ORAL]

-ose¹ (ous) suffix forming nouns 1 a carbohydrate {cellulose, sucrose} 2 the product of a protein hydrolysis {proteose} [Fr < (gluc)ose: see GLUCOSE]

-ose² (ous) suffix forming adjectives full of, having the qualities of, like {filose} [L -osus]

OSHA (ou´shэ) Occupational Safety and Health Administration

Oshawa (äsh´э wэ, -wö) city in SE Ontario, Canada, on Lake Ontario: pop. 124,000

Oshkosh (äsh´käsh) city in E Wis., on Lake Winnebago: pop. 55,000 [after Oshkosh (1795-1858), Menomini chief]

osier (ou´zhэr) •n. 1 any of various willows (esp. Salix viminalis and S. purpurea) whose lithe branches or stems are used for baskets and furniture 2 a willow branch used for wickerwork Æ 3 any of several North American dogwoods [ME osiere < OFr < ML auseria, willow]

Osiris (ou sai´ris) Egypt. Myth. the god of the lower world and judge of the dead, brother and husband of Isis [L < Gr < Egypt Us-år]

-osis (ou´sis) suffix forming nouns 1 state, condition, action {hypnosis} 2 an abnormal or diseased condition {psychosis, mycosis} 3 increase or formation {leukocytosis} [L < Gr -ōsis < -ō-, -o-, ending of preceding verbal or substantive stem + -sis]

-osity (äs´э ti:) suffix forming nouns the quality of being (as specified) Corresponds to -OSE², -OUS [< Fr or L: Fr -osité < L -ositas: see -OSE², -ITY]

OSlav Old (Church) Slavonic

Oslo (äs´lou, äz´-; Norw us´lu) capital of Norway: seaport on an inlet (Oslo Fjord) of the Skagerrak: pop. 447,000

Osman (äz´mэn, äs´-; Turk äs´män´) c. 1259-1326; Turkish leader & founder of the Ottoman dynasty [Turk Othman < Ar Uthmān]

Osmanli (äs mæn´li:, äz-) •n. 1 pl. -lis an Ottoman Turk 2 TURKISH •adj. TURKISH [Turk < prec. + -li, adj. particle]

osmic (äz´mik, äs´-) •adj. designating or of chemical compounds in which osmium has a higher valence than in the corresponding osmous compounds

osmics (äs´miks, äz´-) •n.pl. [with sing. v.] the science dealing with smells and the sense of smell [< Gr osmē, Attic var. of odmē, odor (akin to L odor, ODOR) + -ICS]

osmiridium (äs'mэ rid´i: эm, äz'-) •n. IRIDOSMINE [fol. + IRIDIUM]

osmium (äz´mi: эm, äs´-) •n. a very hard, bluish-white, amorphous, metallic chemical element of the platinum group: it occurs in the form of an alloy with platinum and iridium and is used in pen points, electric light filaments, etc., and as a catalyst: symbol, Os; at. wt., 190.2; at. no., 76; sp. gr., 22.61; melt. pt., 3,045° C; boil. pt., 5,027° C [ModL: so named (1804) by S. Tennant (1761-1815), Eng chemist < Gr osmē, ODOR (from the odor of one of its oxides) + -IUM]

osmometer (äs mäm´эt эr, äz-) •n. an instrument for measuring osmotic pressure [< Gr ōsmos (see OSMOSIS) + METER²]

osmose (äs´mous', äz´-; äs mous´, äz-) -mosed, -mos·ing •vt., vi. to subject to, or undergo, osmosis [back-form. < fol.]

osmosis (äs mou´sis, äz-) •n. 1 the tendency of a solvent to pass through a semipermeable membrane, as the wall of a living cell, into a solution of higher concentration, so as to equalize concentrations on both sides of the membrane 2 the diffusion of fluids through a membrane or porous partition 3 an apparently effortless absorption of ideas, feelings, attitudes, etc., as if by biological osmosis os·mot´ic (-mät´ik) •adj. os·mot´i·cal·ly •adv., n. [ModL, ult. < Gr ōsmos, impulse < ōthein, to push < IE base *wedh-, to push, strike > Sans vádhar-, deadly weapon]

osmotic pressure the pressure exerted by a solvent passing through a semipermeable membrane in osmosis, equal to the pressure that must be applied to the solution in order to prevent passage of the solvent into it

osmous (äz´mэs, äs´-) •adj. designating or of chemical compounds in which osmium has a lower valence than in the corresponding osmic compounds

osmunda (äs mûn´dэ, äz-) •n. any of a genus (Osmunda, family Osmundaceae) of ferns having specialized fronds or portions of fronds bearing dense masses of spore cases [ModL < OFr osmonde < ?]

osmundine (äs mûn´din, äz-; -di:n'; äs´mэn-, äz´-) •n. a fibrous mass of dried fern roots, used as a rooting medium for orchids or other air plants [< prec. + -INE³]

Osnabrück (ôs'nä břük´; E äz´nэ bruk') city in NW Germany, in the state of Lower Saxony: pop. 155,000

osnaburg (äz´nэ børg') •n. a type of coarse, heavy cloth, orig. of linen and now of cotton, used in making sacks, work clothes, etc. [altered after prec., where orig. made]

OSp Old Spanish

osprey (äs´pri:, -prei) pl. -preys •n. a large, black-and-white diving bird of prey of a family (Pandionidae) having only one species (Pandion haliaetus): it feeds mainly on fish [LME ospray, ult. < L ossifraga, osprey, lit., the bone-breaker < os, a bone (see OSSIFY) + frangere, to BREAK]

OSS Office of Strategic Services

Ossa (äs´э) mountain in Thessaly, NE Greece: 6,490 ft. (1,978 m): see PELION ossa (äs´э) •n. pl. of OS²

ossein (äs´i: in) •n. Biochem. the organic basis of bone, the part left after the mineral matter is dissolved in dilute acids [< L osseus, bony < os, a bone (see OSSIFY) + -IN¹]

osseous (äs´i: эs) •adj. composed of, containing, or like bone; bony [L osseus < os, a bone: see OSSIFY]

Osset (äs´et') •n. a member of a people of Ossetia, a region in the N Caucasus Also Os´sete' (-i:t') Os·se·tian (ä si:´shэn) •adj., n.

Ossetic (ä set´ik) •adj. of the Ossets; Ossetian •n. the Iranian language of the Ossets

Ossian (äsh´эn, äs´i: эn) Gael. Folklore a bard and hero of the 3d cent.: James Macpherson published pieces of poetic prose (1761-65) which he falsely claimed were his translations of Ossian's poetry from old Gaelic manuscripts Os·si·an·ic (äs'i: æn´ik, äsh'-) •adj. [Gael Oisīn, dim. of os, a fawn]

ossicle (äs´i kэl) •n. a small bone or bonelike structure; esp., any of the three small bones in the tympanic cavity of the ear os·sic·u·lar (ä sik´yu: lэr) or os·sic´u·late (-lit, -leit') •adj. [< L ossiculum, dim. of os, a bone: see OSSIFY]

Ossietzky (ôs'i: et´ski:), Carl von (käřl fôn) 1889-1938; Ger. journalist & pacifist

ossiferous (ä sif´эr эs) •adj. containing bones, as a geologic deposit [< L os, a bone (see OSSIFY) + -FEROUS]

ossifrage (äs´э frij) •n. [Archaic] 1 LAMMERGEIER 2 OSPREY [L ossifraga, OSPREY]

ossify (äs´э fai') -fied', -fy'ing •vt., vi. 1 to change or develop into bone 2 to settle or fix rigidly in a practice, custom, attitude, etc. os'si·fi·ca´tion •n. [< L os (gen. ossis), a bone (< IE base *ost- > Sans ásthi, Gr osteon, bone) + -FY]

osso buco (ôs´sô bu:´kô) an Italian dish consisting of veal shanks stewed in white wine with tomatoes, garlic, minced vegetables, etc. [It, marrowbone]

ossuary (äs´yu: er'i:) pl. -ar'ies •n. a container, as an urn, vault, etc., for the bones of the dead [LL ossuarium < ossuarius, of or for bones < L os: see OSSIFY]

osteal (äs´ti: эl) •adj. osseous; bony [< Gr osteon, a bone (see OSSIFY) + -AL]

osteitis (äs'ti: ait'is) •n. inflammation of the bone or bony tissue [OSTE(O)- + -ITIS]

Ostend (äs tend´, äs´tend) seaport in NW Belgium, on the North Sea: pop. 69,000: Fr. name Ost·ende (ô stäñd´)

ostensible (ä sten´sэ bэl) •adj. 1 apparent; seeming; professed 2 [Rare] clearly evident os·ten´si·bly •adv. [Fr < ML ostensibilis < L ostendere, to show < ob(s)-, against (see OB-) + tendere, to stretch: see THIN]

ostensive (ä sten´siv) •adj. 1 directly pointing out; clearly demonstrative 2 OSTENSIBLE (sense 1) os·ten´sive·ly •adv. [Fr ostensif < ML ostensivus]

ostentation (äs'tэn tei´shэn) •n. showy display, as of wealth, knowledge, etc.; pretentiousness os'ten·ta´tious •adj. os'ten·ta´tious·ly •adv. os'ten·ta´tious·ness •n. [ME ostentacioun < L ostentatio < ostentare < ostendere: see OSTENSIBLE]

osteo- (äs´ti: ou', -э) combining form bone or bones {osteopathy} Also, before a vowel, oste- [ModL < Gr osteon, a bone: see OSSIFY]

osteoarthritis (äs'ti: ou'är θrait´is) •n. a slowly progressive form of arthritis, found chiefly in older people, characterized by cartilage deterioration and bone enlargement [prec. + ARTHRITIS]

osteoblast (äs´ti: ou blæst') •n. any cell which develops into bone or secretes substances producing bony tissue os'te·o·blas´tic •adj. [OSTEO- + -BLAST]

osteoclasis (äs'ti: äk´lэ sis) •n. 1 the breaking down and absorption of bony tissue 2 the breaking of a bone to correct a deformity, esp. after a badly healed previous fracture [ModL < OSTEO- + Gr klasis, a breaking < klan, to break: see CLASTIC]

osteoclast (äs´ti: ou klæst') •n. 1 any of the large multinucleate cells in bone which absorb or break down bony tissue 2 an instrument used to perform osteoclasis [< OSTEO- + Gr klastos: see CLASTIC]

osteoid (äs´ti: oid') •adj. like bone [OSTE(O)- + -OID]

osteology (äs'ti: äl´э ji:) •n. the study of the structure and function of bones os'te·o·log´i·cal (-ou läj´i kэl) •adj. os'te·ol´o·gist •n. [ModL: see OSTEO- & -LOGY]

osteoma (äs'ti: ou´mэ) pl. -mas or -ma·ta (-mэ tэ) •n. a tumor composed of bony tissue [ModL: see OSTEO- & -OMA]

osteomalacia (äs'ti: ou mэ lei´shэ, -shi: э) •n. a bone disease characterized by a softening of the bones, resulting from deficient bone calcification [ModL < OSTEO- + malacia, a softening of tissue < Gr malakia, softness < malakos, soft: see MALACO-]

osteomyelitis (-mai'э lait´is) •n. infection of bone marrow or bone structures, usually caused by a bacterium (genus Staphylococcus) that produces pus [ModL: see OSTEO- & MYELITIS]

osteopath (äs´ti: ou pæθ', -ti: э-) •n. a doctor who practices osteopathy

osteopathy (äs'ti: äp´э θi:) •n. a school of medicine and surgery employing various methods of diagnosis and treatment, but placing special emphasis on the interrelationship of the musculo-skeletal system to all other body systems os'te·o·path´ic (-ou pæθ´ik) •adj. os'te·o·path´i·cal·ly •adv. [ModL: see OSTEO- & -PATHY]

osteophyte (äs´ti: ou fait') •n. a small bony outgrowth os'te·o·phyt´ic (-fit´ik) •adj. [OSTEO- + -PHYTE]

osteoplastic (äs'ti: ou'plæs´tik) •adj. 1 Anat. of or pertaining to bone formation 2 Surgery of or based on the replacement of bone by restorative operations os´te·o·plas'ty •n. [OSTEO- + -PLASTIC]

osteoporosis (-pэ rou´sis) •n. a bone disorder characterized by a reduction in bone density accompanied by increasing porosity and brittleness, found chiefly in women who have passed menopause [ModL < OSTEO- + porosis, a porous condition < L porus, a PORE² + -OSIS]

osteosis (äs'ti: ou´sis) •n. the formation of bone [ModL: see OSTEO- & -OSIS]

osteotome (äs´ti: ou toum') •n. a surgical instrument for cutting or dividing bone [OSTEO- + -TOME]

osteotomy (äs'ti: ät´э mi:) pl. -mies •n. a surgical operation of dividing a bone or cutting out a piece of bone [OSTEO- + -TOMY]

Österreich (ös´tэř řaiH') Ger. name of AUSTRIA

Ostia (äs´ti: э) ancient city in Latium, at the mouth of the Tiber, that was the port of Rome

Ostiak (äs´ti: æk') •n. OSTYAK

ostiary (äs´ti: er'i:) pl. -ar'ies •n. PORTER¹ [L ostiarius < ostium, door, entrance < os, mouth: see ORAL]

ostinato (äs'tэ nät´ou; It ôs'ti: nä´tô) pl. -tos' (-ouz'; It, -tôs) •n. Music a short melodic phrase persistently repeated by the same voice or instrument and in the same pitch [It, lit., obstinate]

ostiole (äs´ti: oul') •n. a small opening or orifice, as a pore os·ti·o·lar (äs´ti: ou lэr, äs tai´-) •adj. [< ModL ostiolum < L, dim. of ostium: see OSTIARY]

ostium (äs´ti: эm) pl. -ti·a (-э) •n. Anat. an opening or orifice [L ostium: see OSTIARY]

ostler (äs´lэr) •n. HOSTLER (sense 1) [ME osterlere, var. of hostelere: see HOSTLER]

ostomy (äs´tэ mi:) pl. -mies •n. any surgery connecting a hollow organ to the outside of the body or to another hollow organ, as a colostomy

ostosis (äs tou´sis) •n. OSTEOSIS

ostracism (äs´trэ siz'эm) •n. 1 in ancient Greece, the temporary banishment of a citizen by popular vote 2 a rejection or exclusion by general consent, as from a group or from acceptance by society [Gr ostrakismos < ostrakizein: see OSTRACIZE]

ostracize (äs´trэ saiz') -cized', -ciz'ing •vt. to banish, bar, exclude, etc. by ostracism SYN. BANISH [Gr ostrakizein, to exile by votes written on tiles or potsherds < ostrakon, a shell, potsherd, akin to osteon, bone: see OSSIFY]

ostracod (äs´trэ käd') •n. any of various classes (esp. Ostracoda) of small, freshwater or marine crustaceans, having a bivalve carapace that covers the entire body [< ModL Ostracoda < Gr ostrakon: see OSTRACIZE]

Ostrava (ôs´třä vä) city in NE Czech Republic: pop. 324,000

ostrich (äs´trich, ös´-) pl. -trich·es •n.or -trich a swift-running bird (Struthio camelus) of Africa and SW Asia, the only member of its order (Struthioniformes): it is the largest and most powerful of living birds, and has a long neck, very long legs with two toes on each foot, and small, useless wings: the white tail and wing feathers of the male are used in millinery and as trimming [OFr ostrusce < VL avistruthius < L avis, bird + struthio, short for struthiocamelus, ostrich < Gr strouthiokamēlos < strouthos, sparrow + kamēlos, CAMEL]

Ostrogoth (äs´trэ gäθ', -göθ') •n. an East Goth; esp., a member of the tribe which conquered Italy in the 5th cent. A.D. Os'tro·goth´ic •adj. [LL Ostrogothus, earlier Austrogoti (pl.) < Gmc *austra-, EAST + LL Gothi: see GOTH]

Ostwald (oust´vält), Wil·helm (vil´helm) 1853-1932; Ger. chemist, born in Latvia

Ostyak (äs´ti: æk') •n. 1 a member of a Finno-Ugric people living in W Siberia 2 their Ugric language

Oswald (äz´wэld, -wöld') a masculine name: dim. Ozzie [OE Osweald < os, a god + weald, power: for IE base see WIELD]

Oswego tea (äs wi:´gou) 1 a North American mint (Monarda didyma) with dense terminal heads of brilliant-red flowers 2 the tea brewed from its leaves [after the Oswego River, in New York]