orchard (n.) Look up orchard at Dictionary.com
late Old English orceard "fruit garden," earlier ortgeard, perhaps reduced from wortgeard, from wort "vegetable, plant root" + geard "garden, yard" (the word also meant "vegetable garden" until 15c.); see yard (n.1). First element influenced in Middle English by Latin hortus (in Late Latin ortus) "garden," which also is from the root of yard (n.1).
orchestra (n.) Look up orchestra at Dictionary.com
c.1600, "area in an ancient theater for the chorus," from Latin orchestra, from Greek orkhestra, semicircular space where the chorus of dancers performed, with suffix -tra denoting place + orkheisthai "to dance," intensive of erkhesthai "to go, come," from PIE root *ergh- "to mount" (cognates: Sanskrit rghayati "trembles, rages, raves," rnoti "rises, moves," arnah "welling stream;" Old Persian rasatiy "he comes;" Greek ornynai "to rouse, start;" Latin oriri "to rise," origo "a beginning;" Gothic rinnan, Old English irnan "to flow, run"). In ancient Rome, it referred to the place in the theater reserved for senators and other dignitaries. Meaning "group of musicians performing at a concert, opera, etc." first recorded 1720; "part of theater in front of the stage" is from 1768.
orchestral (adj.) Look up orchestral at Dictionary.com
1811, from orchestra + -al (1).
orchestrate (v.) Look up orchestrate at Dictionary.com
"to compose or arrange (music) for an orchestra," 1855, back-formation from orchestration. The figurative sense is attested from 1883. Related: Orchestrated; orchestrating.
orchestration (n.) Look up orchestration at Dictionary.com
1840, from French orchestration or else a native noun of action from orchestrate.
orchid (n.) Look up orchid at Dictionary.com
1845, introduced by John Lindley in "School Botanty," from Modern Latin Orchideæ (Linnaeus), the plant's family name, from Latin orchis, a kind of orchid, from Greek orkhis (genitive orkheos) "orchid," literally "testicle," from PIE *orghi-, the standard root for "testicle" (cognates: Avestan erezi "testicles," Armenian orjik, Middle Irish uirgge, Irish uirge "testicle," Lithuanian erzilas "stallion"). The plant so called because of the shape of its root. Earlier in English in Latin form, orchis (1560s), and in Middle English it was ballockwort (c.1300; see ballocks). Marred by extraneous -d- in an attempt to extract the Latin stem.
ordain (v.) Look up ordain at Dictionary.com
late 13c., "to appoint or admit to the ministry of the Church," from stem of Old French ordener "place in order, arrange, prepare; consecrate, designate" (Modern French ordonner) and directly from Latin ordinare "put in order, arrange, dispose, appoint," from ordo (genitive ordinis) "order" (see order (n.)). The notion is "to confer holy orders upon." Meaning "to decree, enact" is from c.1300; sense of "to set (something) that will continue in a certain order" is from early 14c. Related: Ordained; ordaining.
ordeal (n.) Look up ordeal at Dictionary.com
Old English ordel, ordal, "trial by physical test," literally "judgment, verdict," from Proto-Germanic noun *uz-dailjam (cognates: Old Saxon urdeli, Old Frisian urdel, Dutch oordeel, German urteil "judgment"), literally "that which is dealt out" (by the gods), from *uzdailijan "share out," related to Old English adælan "to deal out" (see deal (n.1)). Curiously absent in Middle English, and perhaps reborrowed 16c. from Medieval Latin or Middle French, which got it from Germanic.

The notion is of the kind of arduous physical test (such as walking blindfolded and barefoot between red-hot plowshares) that was believed to determine a person's guilt or innocence by immediate judgment of the deity, an ancient Teutonic mode of trial. English retains a more exact sense of the word; its cognates in German, etc., have been generalized.

Metaphoric extension to "anything which tests character or endurance" is attested from 1650s. The prefix or- survives in English only in this word, but was common in Old English and other Germanic languages (Gothic ur-, Old Norse or-, etc.) and originally was an adverb and preposition meaning "out."
order (n.) Look up order at Dictionary.com
early 13c., "body of persons living under a religious discipline," from Old French ordre "position, estate; rule, regulation; religious order" (11c.), from earlier ordene, from Latin ordinem (nominative ordo) "row, rank, series, arrangement," originally "a row of threads in a loom," from Italic root *ord- "to arrange, arrangement" (source of ordiri "to begin to weave;" compare primordial), of unknown origin.

Meaning "a rank in the (secular) community" is first recorded c.1300; meaning "command, directive" is first recorded 1540s, from the notion of "to keep in order." Military and honorary orders grew our of the fraternities of Crusader knights. Business and commerce sense is attested from 1837. In natural history, as a classification of living things, it is first recorded 1760. Meaning "condition of a community which is under the rule of law" is from late 15c.

Phrase in order to (1650s) preserves etymological notion of "sequence." The word reflects a medieval notion: "a system of parts subject to certain uniform, established ranks or proportions," and was used of everything from architecture to angels. Old English expressed many of the same ideas with endebyrdnes. In short order "without delay" is from 1834, American English; order of battle is from 1769.
order (v.) Look up order at Dictionary.com
c.1200, "give order to, to arrange in order," from order (n.). Meaning "to give orders for or to" is from 1540s. Related: Ordered; ordering.
orderly (adv.) Look up orderly at Dictionary.com
late 15c., "in due order," from order + -ly (2).
orderly (adj.) Look up orderly at Dictionary.com
"arranged in order," 1570s, from order (n.) + -ly (1).
orderly (n.) Look up orderly at Dictionary.com
"military attendant who carries orders," 1781, short for orderly corporal, etc. Extended 1809 to an attendant at a hospital (originally a military hospital) charged with keeping things in order and clean. See orderly (adj.).
ordinal (n.) Look up ordinal at Dictionary.com
early 14c., "book setting forth the order of services in the Church," from Late Latin adjective ordinalis (see ordinal (adj.)).
ordinal (adj.) Look up ordinal at Dictionary.com
late 14c., "regular, ordinary," from Old French ordinel and directly from Late Latin ordinalis ""showing order, denoting an order of succession," from Latin ordo (genitive ordinis) "row, series" (see order (n.)). Meaning "marking position in an order or series" is from 1590s.
ordinance (n.) Look up ordinance at Dictionary.com
c.1300, "an authoritative direction, decree, or command" (narrower or more transitory than a law), from Old French ordenance (Modern French ordonnance) or directly from Medieval Latin ordinantia, from Latin ordinantem (nominative ordinans), present participle of ordinare "put in order" (see ordain). By early 14c. senses had emerged of "arrangement in ranks or rows" (especially in order of battle), also "warlike provisions, equipment" (a sense now in ordnance).
ordinary (adj.) Look up ordinary at Dictionary.com
early 15c., "belonging to the usual order or course," from Old French ordinarie "ordinary, usual" and directly from Latin ordinarius "customary, regular, usual, orderly," from ordo (genitive ordinis) "order" (see order (n.)). Its various noun usages, dating to late 14c. and common until 19c., now largely extinct except in out of the ordinary (1893). In British education, Ordinary level (abbrev. O level), "lowest of the three levels of General Certificate of Education," is attested from 1947. Related: Ordinarily.
ordinate (adj.) Look up ordinate at Dictionary.com
late 14c., from Latin ordinatus, past participle of ordinare "arrange, set in order" (see ordain). Related: Ordinately.
ordinate (v.) Look up ordinate at Dictionary.com
1560s, from Latin ordinatus, past participle of ordinare "arrange, set in order" (see ordain). Related: Ordinated; ordinating.
ordination (n.) Look up ordination at Dictionary.com
early 15c., "the act of conferring holy orders," from Old French ordinacion (12c.) or directly from Latin ordinationem (nominative ordinatio) "a setting in order, ordinance," noun of action from past participle stem of ordinare "arrange" (see ordain).
ordnance (n.) Look up ordnance at Dictionary.com
"cannon, artillery," 1540s, a clipped form of ordinance (q.v.) which was attested from late 14c. in the sense of "military materials, provisions of war;" a sense now obsolete but which led to those of "engines for discharging missiles" (early 15c.) and "branch of the military concerned with stores and materials" (late 15c.). The shorter word was established in these distinct senses by 17c. Ordnance survey (1833), official survey of Great Britain and Ireland, was undertaken by the government under the direction of the Master-General of the Ordnance (a natural choice, because gunners have to be skilled at surveying ranges and distances).
Ordovician (adj.) Look up Ordovician at Dictionary.com
geological period following the Cambrian and preceding the Silurian, 1879, coined by English geologist Charles Lapworth (1842-1920) from Latin Ordovices, name of an ancient British tribe in North Wales. The period so called because rocks from it first were studied extensively in the region around Bala in North Wales. The tribe's name is Celtic, literally "those who fight with hammers," from Celtic base *ordo "hammer" + PIE *wik- "to fight, conquer" (see victor).
ordure (n.) Look up ordure at Dictionary.com
late 14c., from Old French ordure "filth, uncleanliness" (12c.), from ord, ort "filthy, dirty, foul," from Latin horridus "dreadful" (see horrid).
ore (n.) Look up ore at Dictionary.com
12c., a merger of Old English ora "ore, unworked metal" (related to eorþe "earth," see earth; and cognate with Low German ur "iron-containing ore," Dutch oer, Old Norse aurr "gravel"); and Old English ar "brass, copper, bronze," from Proto-Germanic *ajiz- (cognates: Old Norse eir "brass, copper," German ehern "brazen," Gothic aiz "bronze"), from PIE root *aus- (2) "gold" (see aureate). The two words were not fully assimilated till 17c.; what emerged has the form of ar but the meaning of ora.
ore rotundo Look up ore rotundo at Dictionary.com
Latin, literally "with round mouth," from ablative of os "mouth" (see oral) + ablative of rotundus "round" (see rotund). From Horace ("Grais ingenium, Grais dedit ore rotundo Musa loqui," in "Ars Poetica").
oread (n.) Look up oread at Dictionary.com
1580s, from Latin Oreas (genitive Oreadis), from Greek Oreias "mountain nymph," from oros "mountain," perhaps from PIE root *ergh- "to mount" (see orchestra).
oregano (n.) Look up oregano at Dictionary.com
1771, from Spanish or American Spanish oregano, from Latin origanus, origanum, from Greek oreiganon, from oros "mountain" (see oread) + ganos "brightness, ornament." The older form of the word in English was the Latin-derived origanum (mid-13c.), also origan (early 15c.). In Europe, the dried leaves of wild marjoram; in America, a different, and more pungent, shrub.
Oregon Look up Oregon at Dictionary.com
1765 as the name of a large river in the west of North America, probably the modern Columbia; of uncertain and disputed origin. It seems to be of Algonquian origin. From 1848 as the name of a U.S. territory (admitted as a state 1859).
Oreo (n.) Look up Oreo at Dictionary.com
derogatory word for "black person felt to have a 'white' mentality," 1968, black American English, from the snack cookies, which consist of dark chocolate wafers and white sugar cream filling (hence "brown outside, white inside"). The cookies (made by Nabisco) date from 1912; the source of the name has been forgotten.
Orestes Look up Orestes at Dictionary.com
son of Agamemnon and Clytaemnestra, from Greek Orestes, literally "mountaineer," from oros "mountain" (see oread).
organ (n.) Look up organ at Dictionary.com
fusion of late Old English organe, and Old French orgene (12c.), both meaning "musical instrument," both from Latin organa, plural of organum "a musical instrument," from Greek organon "implement, tool for making or doing; musical instrument; organ of sense, organ of the body," literally "that with which one works," from PIE *werg-ano-, from root *werg- "to do" (cognates: Greek ergon "work," orgia "religious performances;" Armenian gorc "work;" Avestan vareza "work, activity;" Gothic waurkjan, Old English wyrcan "to work," Old English weorc "deed, action, something done;" Old Norse yrka "work, take effect").

Applied vaguely in late Old English to musical instruments; sense narrowed by late 14c. to the musical instrument now known by that name (involving pipes supplied with wind by a bellows and worked by means of keys), though Augustine (c.400) knew this as a specific sense of Latin organa. The meaning "body part adapted to a certain function" is attested from late 14c., from a Medieval Latin sense of Latin organum. Organist is first recorded 1590s; organ-grinder is attested from 1806.
organdy (n.) Look up organdy at Dictionary.com
"fine transparent muslin," 1829, from French organdi "sorte de Mousseline ou toile de coton" (1725), of unknown origin. Barnhart suggests it is an alteration of Organzi, from medieval form of Urgench, city in Uzbekistan that was a cotton textile center.
organelle (n.) Look up organelle at Dictionary.com
1909, from Modern Latin organella, a diminutive from Latin organum "instrument," in Medieval Latin "organ of the body" (see organ).
organic (adj.) Look up organic at Dictionary.com
1510s, "serving as an organ or instrument," from Latin organicus, from Greek organikos "of or pertaining to an organ, serving as instruments or engines," from organon "instrument" (see organ). Sense of "from organized living beings" is first recorded 1778 (earlier this sense was in organical, mid-15c.). Meaning "free from pesticides and fertilizers" first attested 1942. Organic chemistry is attested from 1831.
organically (adv.) Look up organically at Dictionary.com
1680s in reference to bodily organs; 1862 in reference to living beings; 1841 as "as part of an organized whole;" from organic. From 1971 as "without the use of pesticides, etc."
organisation (n.) Look up organisation at Dictionary.com
chiefly British English spelling of organization. For spelling, see -ize. Related: Organisational.
organiser (n.) Look up organiser at Dictionary.com
chiefly British English spelling of organizer (q.v.); for spelling, see -ize.
organism (n.) Look up organism at Dictionary.com
1660s, "organic structure, organization," from organize + -ism. Sense of "living animal or plant" first recorded 1842. Related: Organismic.
organist (n.) Look up organist at Dictionary.com
1590s, from organ + -ist, or from or influenced by Middle French organiste, from Medieval Latin organista "one who plays an organ," from Latin organum (see organ).
organization (n.) Look up organization at Dictionary.com
mid-15c., "act of organizing," from Middle French organisation and directly from Medieval Latin organizationem (nominative organizatio), noun of action from past participle stem of organizare, from Latin organum "instrument, organ" (see organ). Meaning "system, establishment" is from 1873. Organization man is from title of 1956 book by American sociologist William H. Whyte (1917-1999). Related: Organizational.
organize (v.) Look up organize at Dictionary.com
early 15c., "construct, establish," from Middle French organiser and directly from Medieval Latin organizare, from Latin organum "instrument, organ" (see organ). Related: Organized; organizing.
organized (adj.) Look up organized at Dictionary.com
1590s, "furnished with organs," past participle adjective from organize (v.). Meaning "forming a whole of interdependent parts" is from 1817. Organized crime attested from 1929.
organizer (n.) Look up organizer at Dictionary.com
1849, agent noun from organize.
organza (n.) Look up organza at Dictionary.com
1820, from French organsin (1660s), from Italian organzino, of unknown origin; perhaps from the same source as organdy.
orgasm (n.) Look up orgasm at Dictionary.com
1680s, "sexual climax," from French orgasme or Modern Latin orgasmus, from Greek orgasmos "excitement, swelling," from organ "be in heat, become ripe for," literally "to swell, be excited," related to orge "impulse, excitement, anger," from PIE root *wrog- "to burgeon, swell with strength" (cognates: Sanskrit urja "a nourishment, sap, vigor," Old Irish ferc, ferg "anger"). Also used 17c. of other violent excitements of emotion or other bodily functions.
orgasm (v.) Look up orgasm at Dictionary.com
1973, originally and usually in reference to a woman's sexual climax, from orgasm (n.). Related: Orgasmed; orgasming.
orgasmic (adj.) Look up orgasmic at Dictionary.com
1935, from orgasm (n.). + -ic.
orgiastic (adj.) Look up orgiastic at Dictionary.com
1690s, from Greek orgiastikos "fit for orgies, exciting," from orgiastes "one who celebrates orgies," from orgiazein "to celebrate orgies," from orgia (see orgy).
orgy (n.) Look up orgy at Dictionary.com
1560s, orgies (plural) "secret rites in the worship of certain Greek and Roman gods," especially Dionysus, from Middle French orgies (c.1500, from Latin orgia), and directly from Greek orgia (plural) "secret rites," especially those of Bacchus, from PIE root *werg- "to do" (see organ). The singular, orgy, was first used in English 1660s for the extended sense of "any licentious revelry." OED says of the ancient rites that they were "celebrated with extravagant dancing, singing, drinking, etc.," which gives "etc." quite a workout.
oriel (n.) Look up oriel at Dictionary.com
"large recessed window," mid-14c., from Old French oriol "hall, vestibule; oriel," of uncertain origin, perhaps from Medieval Latin oriolum "porch, gallery" (mid-13c.), perhaps from Vulgar Latin *auraeolum, dissimilated from aulaeolum, a diminutive of Latin aulaeum "curtain." Despite much research, the sense evolution remains obscure.