Online Etymology Dictionary

tush (n.): "backside, buttocks," 1962, an abbreviation of tochus (1914), from Yiddish tokhes, from Hebrew tahat "beneath."
tush (interj.): mid-15c.; see tut. Related: Tushery.
tushy (n.): also tushie, 1962, from tush (n.) + -y (3).
tusk (n.): Old English tusc, also transposed as tux, "long, pointed tooth protruding from the mouth of an animal," cognate with Old Frisian tusk, probably from Proto-Germanic *tunthsk- (source also of Gothic tunþus "tooth"), from an extended form of PIE *dent-, the root of tooth. But "there are no certain cognates outside of the Anglo-Frisian area" [OED].
Tuskegee: place in Alabama, named from a Muskogee tribal town taskeke (first recorded in Spanish as tasquiqui), literally "warriors."
tussive (adj.): "pertaining to cough," 1857, from Latin tussis "a cough," of unknown origin, + -ive.
tussle (v.): "to struggle, scuffle, wrestle confusedly," late 15c. (transitive); 1630s (intransitive), Scottish and northern English variant of touselen (see tousle). Related: Tussled; tussling.
tussle (n.): "a struggle, conflict, scuffle," 1620s (but rare before 19c.), from tussle (v.).
tussock (n.): 1540s, "tuft of hair," of uncertain origin; perhaps a diminutive of earlier tusk (1520s) with the same meaning (and also of obscure origin). Meaning "tuft of grass" is first recorded c. 1600.
tut (interj.): 1520s, along with tush (mid-15c.), a natural interjection expressing impatient or dismissive contempt.
tutee (n.): 1927; see tutor (v.) + -ee.
tutelage (n.): "guardianship," c. 1600, from -age + Latin tutela "a watching, keeping, safeguard, protection," from variant past participle stem of tueri "watch over" (see tutor (n.)). Meaning "instruction" first appeared 1857.
tutelary (adj.): 1610s, from Late Latin tutelarius "a guardian," from Latin tutela "protection, watching" (see tutor (n.)).
tutor (n.): late 14c., "guardian, custodian," from Old French tuteor "guardian, private teacher" (13c., Modern French tuteur), from Latin tutorem (nominative tutor) "guardian, watcher," from tutus, variant past participle of tueri "watch over," of uncertain origin, perhaps from PIE *teue- (1) "pay attention to" (see thews). Specific sense of "senior boy appointed to help a junior in his studies" is recorded from 1680s.
tutor (v.): 1590s, from tutor (n.). Related: Tutored; tutoring.
tutorial (adj.): 1742, from tutor (n.) + -al (1). As a noun, attested from 1923.
tutti-frutti (n.): 1834, from Italian tutti frutti "all fruits," from tutti, plural of tutto "all" (from Latin totus "whole, entire;" see total (adj.)) + frutti, plural of frutto "fruit" (from Latin fructus; see fruit).
tutu (n.): ballet skirt, 1910, from French tutu, alteration of cucu, infantile reduplication of cul "bottom, backside," from Latin culus "bottom, backside, fundament."
tux (n.): 1922, colloquial shortening of tuxedo.
tuxedo (n.): man's evening dress for semiformal occasions, 1889, named for Tuxedo Park, N.Y., a rural resort development for wealthy New Yorkers and site of a country club where it first was worn, supposedly in 1886. The name is an attractive subject for elaborate speculation, and connections with Algonquian words for "bear" or "wolf" were proposed. The authoritative Bright, however, says the tribe's name probably is originally a place name, perhaps Munsee Delaware (Algonquian) p'tuck-sepo "crooked river."
There was a hue and cry raised against the Tuxedo coat upon its first appearance because it was erroneously considered and widely written of as intended to displace the swallow tail. When the true import of the tailless dress coat came to be realized it was accepted promptly by swelldom, and now is widely recognized as one of the staple adjuncts of the jeunesse dorée. ["Clothier and Furnisher," August, 1889]
TV (n.): 1948, shortened form of television (q.v.). Spelled out as tee-vee from 1949. TV dinner (1954), made to be eaten from a tray while watching a television set, is a proprietary name registered by Swanson & Sons, Omaha, Nebraska, U.S.
TWA: formed May 16, 1928, as Transcontinental Air Transport, merged 1930 with Western Air Express to form Transcontinental and Western Air Inc. (TWA). Name changed to Trans World Airlines 1950, but the moniker remained the same. Its last remnants were bought out by rival American Airlines in April 2001.
twa (n.): Scottish form of two.
twaddle (n.): "silly talk, prosy nonsense," 1782, probably from twattle (1550s), of obscure origin.
twain (n.): Old English twegen "two" (masc. nominative and accusative), from Proto-Germanic *twa- "two" (see two). It corresponds to Old Frisian twene, Dutch twee, Old High German zwene, Danish tvende. The word outlasted the breakdown of gender in Middle English and survived as a secondary form of two, especially in cases where the numeral follows a noun. Its continuation into modern times was aided by its use in KJV and the Marriage Service, in poetry (where it is a useful rhyme word), and in oral use where it is necessary to be clear that two and not to or too is meant. In U.S. nautical use as "a depth of two fathoms" from 1799.
twang (n.): 1550s, of imitative origin. Originally the sound of plucked bows and strings; extension to "a nasal vocal sound" is first recorded 1660s. The verb is first attested 1540s. Related: Twanged; twanging.
twangy (adj.): 1858, from twang (n.) + -y (2). Related: Twangily; twanginess.
twat (n.): female pudendum, 1650s, of unknown origin. A general term of abuse since 1920s.
The T-word occupies a special niche in literary history, however, thanks to a horrible mistake by Robert Browning, who included it in 'Pippa Passes' (1841) without knowing its true meaning. 'The owls and bats,/Cowls and twats,/Monks and nuns,/In a cloister's moods.' Poor Robert! He had been misled into thinking the word meant 'hat' by its appearance in 'Vanity of Vanities,' a poem of 1660, containing the treacherous lines: 'They'd talk't of his having a Cardinalls Hat,/They'd send him as soon an Old Nuns Twat.' (There is a lesson here about not using words unless one is very sure of their meaning.) [Hugh Rawson, "Wicked Words," 1989]
tweak (v.): "pinch, pluck, twist," usually to the nose, c. 1600, probably from Middle English twikken "to draw, tug, pluck" (mid-15c.), from Old English twiccian "to pluck," of obscure origin; perhaps related to twitch. Meaning "to make fine adjustments" is attested from 1966. Related: Tweaked; tweaking.
tweak (n.): c. 1600, "a twitch, a pluck," from tweak (v.). As "a fine adjustment" by 1989.
twee (adj.): "tiny, dainty, miniature," 1905, from childish pronunciation of sweet (adj.). Compare tummy from stomach.
tweed (n.): 1839, a trade name for a type of woolen fabric:
MICHAEL NOWAK, alias John Mazurkiewiez, was indicted for stealing on the 15th of April 2 ¼ yards of woollen cloth, called tweed, value 12s., and 2 ¼ yards of woollen cloth, called doe skin, value 17s., the goods of George Priestley Heap. [London Central Criminal Court minutes of evidence from 1839]
This apparently developed from the "Tweed Fishing or Travelling Trousers" advertised in numerous publications from 1834-1838 by the clothing house of Doudney & Son, 49 Lombard Street.
So celebrated has amateur rod-fishing in the Tweed become, that the proper costume of the sportsman has now become an object of speculation among the London tailors, one of whom advertises among other articles of dress "Tweed Fishing Trousers." The anglers who have so long established their head-quarters at Kelso, for the purpose of enjoying the amusement of salmon fishing in the Tweed, have had excellent sport lately : some of the most skilful having caught five or six salmon a day, weighing from six to fourteen pounds each. ["New Sporting Magazine," June 1837]
Thus ultimately named for the River Tweed in Scotland. The place name has not been explained, and it is perhaps pre-Celtic and non-Indo-European.
tweedledum (n.): paired with tweedledee to signify two things or persons nearly alike, differing in name, 1725, coined by English poet John Byrom (1692-1767) in his satire "On the Feud Between Handel and Bononcini," a couple of competing musicians, from tweedle "to sing, to whistle" (1680s), of imitative origin. The -dum and -dee perhaps suggest low and high sounds respectively.
tweedy (adj.): "characteristic of the country or suburban set," 1912, from tweed + -y (2). Related: Tweediness.
tween (prep.): also 'tween, c. 1300 as an abbreviation of between. As a noun meaning "child nearing puberty" (approximately ages 9 to 12), attested by 1988, in this case by influence of teen. Tolkien uses it in "Lord of the Rings" for "the irresponsible twenties between [Hobbit] childhood and coming of age at thirty-three." Earlier in this sense was subteen (1952). Related: Tweens. Tweenie or tweeny was a term (late 19c.-early 20c.) for "between-maid, a servant who assists two others" and was used in reference to other persons or objects in intermediary situations. And 'tween-age (adj.) was used in descriptions of clothing from 1937. Tween-ager is attested from 1946.
tweet (n.): 1845, imitative of the sound made by a small bird. As a verb by 1872. Related: Tweeted; tweeting. As the word for what one does on the Twitter microblogging service, by 2007.
tweeter (n.): "loudspeaker for high frequencies," 1934, agent noun from tweet (v.).
tweeze (v.): "to pluck with tweezers," 1921, back-formation from tweezers. Related: Tweezed; tweezing. Earlier verb was tweezer (1806).
tweezers (n.): "small pincers, diminutive tongs," 1650s, extended from tweezes, plural of tweeze "case for tweezers" (1620s), a shortening of etweese, considered as plural of etwee (1610s) "a small case," from French étui "small case" (see etui). Sense transferred from the case to the implement inside it. For form, compare trousers from trouzes.
twelfth (adj.): late 14c., with -th (1), altering Middle English twelfte, from Old English twelfta, from twelf ((see twelve). The earlier form is cognate with Old Norse tolfti, Danish tolvte, Old Frisian twelefta, Dutch twaalfde, Old High German zwelifto, German zwölfte .

As a noun meaning "a twelfth part," from 1550s. Twelfth Night is Old English twelftan niht "Twelfth Night," the eve of Epiphany, which comes twelve days after Christmas, formerly an occasion of social rites and a time of merrymaking.
twelve (adj.): Old English twelf "twelve," literally "two left" (over ten), from Proto-Germanic *twa-lif-, a compound of the root of two + *lif-, root of the verb leave (see eleven). Compare Old Saxon twelif, Old Norse tolf, Old Frisian twelef, Middle Dutch twalef, Dutch twaalf, Old High German zwelif, German zwölf, Gothic twalif. Outside Germanic, an analogous formation is Lithuanian dvylika, with second element -lika "left over."
twelve-month (n.): "a year," Old English twelf-monð; see twelve + month.
twenties (n.): 1829 as the years of someone's life between 20 and 29; 1830 as the third decade of years in a given century. See twenty.
twentieth (adj.): 16c., from twenty + -th (1), replacing Middle English twentithe, from Old English twentigoða. The Twentieth Century Limited was an express train from New York to Chicago 1902-1967.
twenty (n.): Old English twentig "group of twenty," from twegen "two" (see two) + -tig "group of ten" (see -ty (1)). Cognate with Old Saxon twentig , Old Frisian twintich, Dutch twintig, Old High German zweinzug, German zwanzig. Gothic twai tigjus is even more transparent: literally "two tens."

The card game twenty-one (1790) is from French vingt-et-un (1781). Twenty-twenty hindsight is first recorded 1962, a figurative use of the Snellen fraction for normal visual acuity, expressed in feet. The guessing game of twenty questions is recorded from 1786.
twerk (v.): "to dance in a way that simulates the body's action in copulation," by 2005, alteration of twurk, which seems to have originated in the Atlanta, Georgia, strip club and hip-hop scene and first came to wide attention in the Ying Yang Twins' 2000 song "Whistle While You Twurk," described as "an ode to strippers" ["Country Fried Soul, Adventures in Dirty South Hip-Hop"]. Probably ultimately imitative of something. Related: Twerked; twerking. There is a verb twirk from 1599, "to pull, tug, twirl," what a man does with his mustache, but OED regards this as possibly a misprint of twirl.
twerp (n.): of unknown origin; OED and Barnhart give earliest date as 1925, but the "Dictionary of American Slang" gives a first reference of 1874 (but without citation and I can't find it), which, if correct, would rule out the usual theory that it is from the proper name of T.W. Earp, a student at Oxford c. 1911, who kindled wrath "in the hearts of the rugger-playing stalwarts at Oxford, when he was president of the Union, by being the last, most charming, and wittiest of the 'decadents.' " [Rawson]
"Mean to say you never heard of Sinzy? Why, he's one of the greatest characters in this town. He's a terrible twerp to look at -- got a face like bad news from home, but I guess he's the best jazz piano player in the world." [Julian Street, "Cross-Sections," 1923]
Twi (n.): chief language of Ghana in West Africa; also known as Akan, it is in the Niger-Congo language family.
twi-: word-forming element meaning "two, twice, double, in two ways," from Old English twi- "two, in two ways, twice, double," from Proto-Germanic *twi- (source also of Old Frisian twi-, Old Norse tvi-, Dutch twee-, Old High German zwi-, German zwei-), from PIE *dwis (source also of Sanskrit dvi-, Greek di-, Old Latin dvi-, Latin bi-, Lithuanian dvi-), from *dwo "two" (see two). Cognate with bi-. Older instances of it include Middle English twinter "two years old" (c. 1400, of cattle, sheep, etc.), reduced from Old English twi-wintre, and Old English twispræc "double or deceitful speech."
twi-night (adj.): 1939, in reference to evening double-header baseball games, from twilight + night.