Online Etymology Dictionary

quandary (n.): 1570s, "state of perplexity," of unknown origin, perhaps a quasi-Latinism based on Latin quando "when."
quango (n.): 1973, acronym for quasi-non-governmental organization (itself attested from 1967).
quantify (v.): c.1840, as a term in logic, from Medieval Latin quantificare, from Latin quantus "how much" (see quantity) + facere "to make" (see factitious). Literal sense of "determine the quantity of, measure" is from 1878. Related: Quantifiable; quantifiably.
quantitation (n.): 1959, from quantity + -ation. Related: Quantitate.
quantitative (adj.): 1580s, from Medieval Latin quantitativus, from Latin quantitas (see quantity). Related: Quantitatively.
quantitive (adj.): 1650s, from quantity + -ive. Related: Quantitively.
quantity (n.): early 14c., from Old French quantite (Modern French quantité), from Latin quantitatem (nominative quantitas, coined as a loan-translation of Greek posotes) "relative greatness or extent," from quantus "how much," from quam "how, how much." Latin quantitas also is the source of Italian quantita, Spanish cantidad, Danish and Swedish kvantitet, German quantitat.
quantum (n.): 1610s, "one's share or portion," from Latin quantum "how much," neuter singular of quantus "how great" (see quantity). Introduced in physics by Max Planck, 1900; reinforced by Einstein, 1905. Quantum theory is from 1912; quantum mechanics, 1922; quantum jump is first recorded 1955; quantum leap, 1970.
quarantine (n.): 1520s, "period of 40 days in which a widow has the right to remain in her dead husband's house." Earlier (15c.), "desert in which Christ fasted for 40 days," from Latin quadraginta "forty," related to quattuor "four" (see four).

Sense of "period a ship suspected of carrying disease is kept in isolation" is 1660s, from Italian quarantina giorni, literally "space of forty days," from quaranta "forty," from Latin quadraginta. So called from the Venetian custom of keeping ships from plague-stricken countries waiting off its port for 40 days (first enforced at Ragusa late 14c.). The extended sense of "any period of isolation" is from 1670s.
quark (n.): 1964, applied by U.S. physicist Murray Gell-Mann (b.1929), who said he took it from a nonsense word in James Joyce's "Finnegans Wake" (1939).
quarrel (n.1): "angry dispute," mid-14c., "ground for complaint," from Old French querele, from Latin querella "complaint," from queri "to complain, lament." Replaced Old English sacan. Sense of "contention between persons" is from 1570s.
quarrel (n.2): "square-headed bolt for a crossbow," early 13c., from Old French quarel, from Vulgar Latin *quadrellus, diminutive of Late Latin quadrus (adj.) "square," related to quattuor "four" (see four). Archaic sense of "square or diamond-shaped plane of glass" first recorded mid-15c.
quarrel (v.): late 14c., "to raise an objection;" 1520s with the meaning "to contend violently, to fall out," from quarrel (n.1). Related: Quarrelled; quarrelling.
quarrelsome (adj.): 1590s, from quarrel (n.1) + -some. Related: Quarrelsomeness.
quarry (n.1): "what is hunted," early 14c., quirre "entrails of deer placed on the hide and given to dogs of the chase as a reward," from Anglo-French quirreie, Old French cuiriee, altered (by influence of Old French cuir "skin," from Latin corium "hide"), from Old French corée "viscera, entrails," from Vulgar Latin *corata "entrails," from Latin cor "heart." Sense of "anything chased in hunt" is first recorded 1610s; earlier "bird targeted by a hawk or other raptor" (late 15c.).
quarry (n.2): "where rocks are excavated," c.1400, from Medieval Latin quarreria (mid-13c.), literally "place where stones are squared," from Latin quadrare "to square" (see quadrant).
quarry (v.): 1774, from quarry (n.2). Related: Quarried; quarrying.
quart (n.): early 14c., "one-fourth of a gallon," from Old French quarte "a fourth part" (13c.), from Latin quarta (pars), from fem. of quartus "fourth," related to quattuor "four," from PIE root *kewtwor- (see four).
quarter (n.): c.1300, "one-fourth of anything," from Old French quartier (12c.), from Latin quartarius "fourth part," from quartus "fourth" (see quart). Earliest sense is "parts of the body as dismembered during execution" (c.1300). Used of the moon from c.1400 and the hour from 1590s. The coin is peculiar to U.S., first recorded 1783.

Meaning "region, locality" is from c.1300. Meaning "portion of a town" (identified by the class or race of people who live there) is first attested 1520s. Quarter days (late 15c.), when rents were paid and contracts and leases began or expired, were, in England, Lady day (March 25), Midsummer day (June 24), Michaelmas day (Sept. 29), and Christmas day (Dec. 25); in Scotland, keeping closer to the pagan Celtic calendar, they were Candlemas (Feb. 2), Whitsunday (May 15), Lammas (Aug. 1), and Martinmas (Nov. 11). Quarter horse, bred strong for racing on quarter-mile tracks, first recorded 1834.
quarter (v.): "to cut in quarters," early 15c., from quarter (n.). Related: Quartered; quartering. The verb meaning "to put up soldiers" is recorded from 1590s (see quarters).
quarterback (n.): in U.S. football, 1876, from quarter (n.) + back (n.); so called from his position on the field at the start of play between the halfback and the center. As a verb from 1945. Figurative sense from 1952. Monday morning quarterback is 1932 (n.), 1972 (v.); originally pro football player slang for sportswriters (professional football games typically played on Sundays).
quarterly: mid-15c. (adv.); 1560s (adj.), from quarter (n.) + -ly. As a noun, from 1830 with reference to quarterly publications.
quartermaster (n.): early-15c., "subordinate officer of a ship," from French quartier-maître or Dutch kwartier-meester; originally a ship's officer whose duties included stowing of the hold; later (c.1600) an officer in charge of quarters and rations for troops. See quarters.
quarters (n.): "military dwelling place," 1590s, from quarter (n.) in sense of "portion of a town." The military sense is in quartermaster (mid-15c.) and might be behind the phrase give (no) quarter (1610s), on the notion of "to provide a prisoner with shelter."
quarterstaff (n.): 1550s, stout pole, six to eight feet long, tipped with iron, formerly a weapon used by the English peasantry. The exact sense of quarter is uncertain here; it may be from a tree of a certain size cut into quarters.
quartet (n.): 1773, "musical composition for four instruments or voices," from French quartette, from Italian quartetto, diminutive of quarto "fourth," from Latin quartus "fourth" (see quart). Meaning "set of four singers or musical performers" is from 1814.
quartile (n.): mid-15c., from Middle French quartil, from Medieval Latin quartilus "of a quartile," from Latin quartus "fourth" (see quart).
quarto (n.): late 15c., from Medieval Latin in quarto "in the fourth (part of a sheet of paper)," from quarto, ablative singular of Latin quartus "fourth" (see quart).
quartz (n.): 1756, from German Quarz "rock crystal," from Middle High German twarc, probably from a W.Slavic source (cf. Czech tvrdy, Polish twardy "quartz"), from Old Church Slavonic tvrudu "hard."
quasar (n.): 1964, from "quas(i-stell)ar radio source" (1963).
quash (v.): "to make void, annul, crush," early 14c., from Old French quasser "to break, smash," from Latin quassare "to shatter," frequentative of quatere "to shake" (past participle quassus), from PIE root *kwet- "to shake" (cf. Greek passein "to sprinkle"). Meaning "suppress" is from Medieval Latin quassare "make null and void," from Latin cassus "empty, void," influenced by quassare. Related: Quashed; quashing.
quasi: late 15c., Latin, "as if," from quam "as much as" (see quantity) + si "if."
quasi-: word-forming element used since 18c. (but most productively in 20c.) and meaning "kind of, resembling, like but not really;" from Latin quasi "as if, as it were" (see quasi).
quasimodo (n.): "Low Sunday," 1706, Quasimodo Sunday, from Latin quasi modo, first words of introit for the first Sunday after Easter: quasi modo geniti infantes "as newborn babes" (1 Pet. ii:2). The hunchback in Victor Hugo's novel was supposed to have been abandoned as an infant at Notre Dame on this day.
quaternary (adj.): early 15c., "consisting of four parts," from Latin quaternarius "of four each," from quaterni "four each," from quater "four times," related to quattuor "four" (see four). In geological sense, attested from 1843, proposed 1829 by French geologist Jules Pierre François Stanislas Desnoyers (1800-1887) as name for "the fourth great epoch of geological time," but because it only comprises the age of man, and the other epochs are many hundred times longer, not all accepted it.
quatrain (n.): 1580s, from Middle French quatrain "four-line stanza," from Old French quatre "four," from Latin quattuor "four" (see four).
quattrocento (n.): 1875, "the fifteenth century as a period in art and architecture," from Italian, literally "four hundred," short for mille quattrocento "one thousand four hundred."
quaver (v.): "to vibrate, tremble," early 15c., probably frequentative of cwavien "to tremble, shake" (early 13c.), probably related to Low German quabbeln "tremble," possibly of imitative origin. Meaning "sing in trills or quavers" first recorded 1530s. Related: Quavered; quavering. The noun meaning "musical note" is first recorded 1560s.
quay (n.): 1690s, variant of Middle English key "wharf" (c.1400; mid-13c. in place names), from Old North French cai (Old French chai) "sand bank," from Gaulish caium (5c.), from Old Celtic *kagio- "to encompass, enclose" (cf. Welsh cae "fence, hedge," Cornish ke "hedge"), cognate with Old English haga "hedge" (see hedge). Spelling altered by influence of French quai, from the same Celtic source.
quean (n.): "young, robust woman," Old English cwene "woman," also "female serf, hussy, prostitute" (cf. portcwene "public woman"), from Proto-Germanic *kwenon (cf. Old Saxon quan, Old High German quena, Old Norse kona, Gothic qino "wife, woman"); see queen. Popular 16c.-17c. in sense "hussy." Sense of "effeminate homosexual" is recorded from 1935, especially in Australian slang.
queasy (adj.): mid-15c., coysy, possibly from Old Norse kveisa "boil," perhaps influenced by Anglo-French queisier, from Old French coisier "to wound, hurt, make uneasy," from the same Germanic root as kveisa. But history is obscure and evidences of development are wanting. Related: Queasily; queasiness.
Quebec: Canadian French province, from Micmac (Algonquian) /kepe:k/ "strait, narrows."
Quechua (n.): Indian people of Peru and surrounding regions, 1840, from Spanish, from Quechua kechua "plunderer, destroyer." Also the name of their language.
queen (n.): Old English cwen "queen, female ruler of a state, woman, wife," from Proto-Germanic *kwoeniz, ablaut variant of *kwenon (source of quean), from PIE *gwen- "woman, wife" supposedly originally "honored woman" (cf. Greek gyné "a woman, a wife;" Gaelic bean "woman;" Sanskrit janis "a woman," gná "wife of a god, a goddess;" Avestan jainish "wife;" Armenian kin "woman;" Old Church Slavonic zena, Old Prussian genna "woman;" Gothic qino "a woman, wife; qéns "a queen").

The original sense seems to have been "wife," specialized by Old English to "wife of a king." Used of chess piece from mid-15c., of playing card from 1570s. Of bees from c.1600 (until late 17c., they generally were thought to be kings; cf. "Henry V," I.ii). Meaning "male homosexual" (especially a feminine and ostentatious one) first recorded 1924; probably an alteration of quean in this sense. Queen Anne first used 1878 for "style characteristic of the time of Queen Anne of Great Britain and Ireland," who reigned 1702-14.

English is one of the very few Indo-European languages to have a word for "queen" that is not a feminine derivative of a word for "king." The others are Scandinavian: Old Norse drottning, Danish dronning, Swedish drottning "queen," in Old Norse also "mistress," but these also are held to be ultimately from male words, e.g. Old Norse drottinn "master."
Queens: New York City borough, named for Catherine of Braganza, queen of English King Charles II.
Queensberry Rules: drawn up 1867 by Sir John Sholto Douglas (1844-1900), 8th Marquis of Queensberry, to govern the sport of boxing in Great Britain.
queer (adj.): c.1500, "strange, peculiar, eccentric," from Scottish, perhaps from Low German (Brunswick dialect) queer "oblique, off-center," related to German quer "oblique, perverse, odd," from Old High German twerh "oblique," from PIE root *twerk- "to turn, twist, wind" (related to thwart). Sense of "homosexual" first recorded 1922; the noun in this sense is 1935, from the adjective. Related: Queerly; queerness.
queer (v.): "to spoil, ruin," 1812, from queer (adj.). Related: Queered; queering.
quelch (v.): 1650s, shortening of squelch, perhaps influenced by quench. Related: Quelched; quelching.
quell (v.): Old English cwellan "to kill, murder, execute," from Proto-Germanic *kwaljanan (cf. Old English cwelan "to die," cwalu "violent death;" Old Saxon quellian "to torture, kill;" Old Norse kvelja "to torment;" Middle Dutch quelen "to vex, tease, torment;" Old High German quellan "to suffer pain," German quälen "to torment, torture"), from root *kwel-/*kwal- (cf. Armenian kelem "I torture;" Old Church Slavonic zali "pain;" Lithuanian galas "end," gela "agony," gelati "to sting"). Milder sense of "suppress, extinguish" developed by c.1300. Related: Quelled; quelling.