Online Etymology Dictionary

ottava rima: 1820, Italian, "eight-lined stanza," literally "eighth rhyme," from ottava "eighth" (see octave). A stanza of eight 11-syllable lines, rhymed a b a b a b c c, but in the Byronic variety, they are English heroic lines of 10 syllables.
Ottawa: Canadian capital, founded 1827 as Bytown, named for English officer John By, who oversaw construction of the canal there; renamed 1854, when it became capital, for the Ottawa River, which took its name from the Algonquian people who lived in Michigan and Ontario. Their name is said to be from adawe "to trade."
otter (n.): Old English otr, otor "otter," from Proto-Germanic *otraz (source also of Old Norse otr, Swedish utter, Danish odder, Dutch otter, Old High German ottar, German Otter), from PIE *udros, literally "water-creature" (source also of Sanskrit udrah, Avestan udra "otter;" Greek hydra "water-serpent," enydris "otter;" Latin lutra, Old Church Slavonic vydra, Lithuanian udra, Old Irish odoirne "otter"), from root *wed- (1) "water" (see water (n.1)). Sea otter attested from 1660s, also known as sea-ape.
Ottoman: 1580s (n.), c. 1600 (adj.), from French Ottoman, from Italian Ottomano, from Arabic 'Uthmani "of or belonging to 'Uthman," Arabic masc. proper name, which in Turkish is pronounced Othman (see Osmanli), name of the founder of the dynasty and empire. Ending altered in Italian by formation of a new false singular, because -i was a plural inflection in Italian. Byron used the more correct form Othman, and a few writers have followed him. The type of couch so called (1806) because one reclined on it, which was associated with Eastern customs (see couch).
oubliette (n.): "secret dungeon reached only via trapdoor," 1819, from French oubliette (14c.), from Middle French oublier "to forget, show negligence," Old French oblier, oblider, from Vulgar Latin *oblitare, from Latin oblitus, past participle of oblivisci "to forget" (see oblivion).
ouch: 1837, from Pennsylvania German outch, cry of pain, from German autsch. The Japanese word is itai. Latin used au, hau.
oud (n.): "lute or mandolin of Arab lands," 1738, from Arabic 'ud, literally "wood." Compare lute.
ought (v.): Old English ahte "owned, possessed," past tense of agan "to own, possess, owe" (see owe). As a past tense of owe, it shared in that word's evolution and meant at times in Middle English "possessed" and "under obligation to pay." It has been detached from owe since 17c., though he aught me ten pounds is recorded as active in East Anglian dialect from c. 1825. As an auxiliary verb expressing duty or obligation (late 12c., the main modern use), it represents the past subjunctive.
ought (n.): "zero, cipher," 1844, probably a misdivision of a nought (see nought; for misdivision, see N); meaning probably influenced by aught "anything."
oui: Modern French for "yes," from Old French oïl "yes," at first two words meaning "yes, he," or "yes, they," which gradually came to mean simply "yes." From the Latin phrase hoc ille "yes," literally "this he, so he" (did or said).
The French originally said "yes, I," "yes, you," "yes, we," etc., where the pronoun was the subject of an unexpressed verb easily supplied from the question. [Wright, C.H.C., "A History of French Literature," Haskell House, 1969]
Thus the o is from Latin hoc "this," and the rest of it is from the Latin personal pronoun ille "he" (in Vulgar Latin illi which is also "they"). Old French also had o alone as "yes." Compare Languedoc.
Ouija: 1891, a trademark name (originally by Kennard Novelty Co., Baltimore, Md.), compounded from French oui + German ja, both meaning "yes."
ounce (n.1): unit of weight, early 14c., from Old French once, unce, a measure of weight or time (12c.), from Latin uncia "one-twelfth part" (of a pound, foot, etc.), from Latin unus "one" (see one). The Latin word had been adopted in Old English as ynce (see inch). It was one-twelfth of a pound in the Troy system of weights, but one-sixteenth in avoirdupois. Abbreviation oz. is from older Italian onza. Also used in Middle English as a measure of time (7.5 seconds) and length (about 3 inches).
ounce (n.2): "wildcat," c. 1300, from Old French once "lynx" (13c.), from lonce, with l- mistaken as definite article, from Vulgar Latin *luncea, from Latin lyncea "lynx-like," from lynx (see lynx). Originally the common lynx, later extended to other wildcats, now mainly used of the mountain-panther or snow leopard of Asia.
our (pron.): Old English ure "of us," genitive plural of the first person pronoun, from Proto-Germanic *ons (source also of Old Saxon usa, Old Frisian use, Old High German unsar, German unser, Gothic unsar "our"), from PIE *nes-, oblique case of personal pronoun in first person plural (source of Latin nos "we," noster "our"). Also compare ours. Ourselves (late 15c.), modeled on yourselves, replaced original construction we selfe, us selfum, etc.
ours: c. 1300, a double possessive (with genitive suffix -s (1)), originating in northern England, and has taken over the absolute function of our (q.v.). In Middle English ourn, ouren also were used.
oust (v.): early 15c., from Anglo-French oster (late 13c.), Old French oster "remove, take away, take off; evict, dispel; liberate, release" (Modern French ôter), from Latin obstare "stand before, be opposite, stand opposite to, block," in Vulgar Latin, "hinder," from ob "against" (see ob-) + stare "to stand," from PIE root *sta- "to stand" (see stet). Related: Ousted; ousting.
ouster (n.): "ejection from property," 1530s, noun use of Anglo-French ouster (see oust). For other such usages, see waiver.
out (adv.): Old English ut "out, without, outside," common Germanic (Old Norse, Old Frisian, Old Saxon, Gothic ut, Middle Dutch uut, Dutch uit, Old High German uz, German aus), from PIE root *ud- "up, out, up away" (source also of Sanskrit ut "up, out," uttarah "higher, upper, later, northern;" Avestan uz- "up, out," Old Irish ud- "out," Latin usque "all the way to, without interruption," Greek hysteros "the latter," Russian vy- "out"). Meaning "into public notice" is from 1540s. As an adjective from c. 1200. Meaning "unconscious" is attested from 1898, originally in boxing. Sense of "not popular or modern" is from 1966. As a preposition from mid-13c.

Sense in baseball (1860) was earlier in cricket (1746). Adverbial phrase out-and-out "thoroughly" is attested from early 14c.; adjective usage is attested from 1813; out-of-the-way (adj.) "remote, secluded" is attested from late 15c. Out-of-towner "one not from a certain place" is from 1911. Shakespeare's It out-herods Herod ("Hamlet") reflects Herod as stock braggart and bully in old religious drama and was widely imitated 19c. Out to lunch "insane" is student slang from 1955; out of this world "excellent" is from 1938; out of sight "excellent, superior" is from 1891.
out (v.): Old English utian "expel, put out" (see out (adv.)); used in many senses over the years. Meaning "to expose as a closet homosexual" is first recorded 1990 (as an adjective meaning "openly avowing one's homosexuality" it dates from 1970s; see closet); sense of "disclose to public view, reveal, make known" has been present since mid-14c.
Eufrosyne preyde Þat god schulde not outen hire to nowiht. [Legendary of St. Euphrosyne, c. 1350]
Related: Outed; outing.
out (n.): 1620s, "a being out" (of something), from out (adv.). From 1860 in baseball sense; from 1919 as "means of escape; alibi."
out-bid (v.): 1580s, from out (adv.) + bid (v.). Related: Out-bidding; out-bidden.
out-building (n.): "a detached or subordinate building," 1620s, from out + building (n.).
out-take (n.): "rejected part of a film," 1960, from out + take (n.) in the movie sense.
out-thrust (adj.): 1820, from out (adv.) + thrust (v.).
outage (n.): "period or condition in which electrical power is disconnected," 1903, American English; formed from out on model of shortage.
outback (n.): "back-country, interior regions of Australia," 1907, Australian English, originally an adverb, "out in the back settlements" (1878), from out + back (adv.).
outboard (adj.): "situated on the outside of a ship," 1823, from out + board (n.2). In reference to motors, from 1909.
outbreak (n.): "eruption" (of disease, hostilities, etc.), c. 1600, from out + break (v.). Outbreak was a verb in Middle English (c. 1300).
outburst (n.): 1650s, from out + burst (v.). Outbresten was a verb in Middle English (mid-12c.), from Old English utaberstan. Carlyle (1837) apparently coined inburst (n.) to be its opposite.
outcast (n.): mid-14c., "a person cast out or rejected," originally past participle of Middle English outcasten, from out + casten "to cast" (see cast (v.)). The adjective is attested from late 14c. In an Indian context, outcaste "one who has been expelled from his caste" is from 1876; see caste.
outclass (v.): 1870, "to beat (a rival) so completely as to put him out of the same class," from out + class (v.).
outcome (n.): 1788, "that which results from something," originally Scottish, from out + come (v.). Popularized in English by Carlyle (c. 1830s). Used in Middle English in sense of "act or fact of coming out" (c. 1200). Old English had utancumen (n.) "stranger, foreigner."
outcrop (n.): 1805, in geology, "exposure of rocks at the surface," from out + crop (n.) in its sense of "sprout, head."
outcry (n.): mid-14c., "act of crying aloud," from out + cry (v.). In metaphoric sense of "public protest," first attested 1911 in George Bernard Shaw.
outdated (adj.): also out-dated, 1610s, "grown obsolete," from out + past participle of date (v.1). Out-of-date is attested from 1610s.
outdoor (adj.): 1748, from out + door. Out-of-door is from c. 1800.
outdoors (adv.): 1817, from outdoor + adverbial genitive. As a noun, "open spaces," recorded from 1857.
outdoorsman (n.): 1924, American English, from outdoors + man (n.).
outen (v.): "put out," 1916, American English dialectal; see out (adv.) + -en (1). An idiom in Pennsylvania German.
outer (adj.): late 14c., comparative of out (on analogy of inner), replacing by 18c. forms descended from Old English uttera (comp. of Old English ut "out") which developed into utter and was no longer felt as connected with out. Outer space first attested 1901 in writings of H.G. Wells.
outermost (adj.): 1580s, from outer + -most.
outerwear (n.): 1921, from outer + wear (n.).
outface (v.): 1520s, from out (adv.) + face (v.). Related: Outfaced; outfacing.
outfield (n.): 1630s, "outlying land of a farm" (especially in Scotland), from out + field (n.); sporting sense is attested from 1851 in cricket, 1868 in baseball. Related: Outfielder.
outfit (n.): 1769, "act of fitting out (a ship, etc.) for an expedition," from out + fit (v.). Sense of "articles and equipment required for an expedition" first attested 1787, American English; meaning "a person's clothes" is first recorded 1852; sense of "group of people" is from 1883.
outfit (v.): 1840, from outfit (n.). Related: Outfitted; outfitting; outfitter.
outflank (v.): 1765, from out (adv.) + flank (v.). Figurative use from 1773. Related: Outflanked; outflanking.
outflow (n.): 1869, from out (adv.) + flow (n.).
outfox (v.): "outwit," 1939, from out + fox (q.v.). Related: Outfoxed; outfoxing.
outgoing (adj.): 1630s, "that goes out," from out (adv.) + going. Meaning "sociable, friendly," attested from 1950, on same notion as in extrovert. Middle English had a noun outgoing "a departure," mid-14c., from a verb outgo "to go forth," and Old English had utgangende "outgoing" (literal). Related: Outgoingness.