Online Etymology Dictionary

thyroxine (n.): from thyro-, comb. form of thyroid, + oxy- + indole + chemical suffix -ine (2). So called from the original description of its composition.
thyrsus (n.): 1590s, from Greek thyrsos, literally "stalk or stem of a plant," a non-Greek word of unknown origin. The staff or spear tipped with an ornament like a pine cone, and sometimes wreathed in ivy or vine branches, borne by Dionysus and his votaries.
thyself: Middle English þi-self, from Old English þe self; see thy + self. One word from 16c.
Tia Maria (n.): coffee-flavored, rum-based liqueur, originally made in the West Indies, 1948, Spanish, literally "Aunt Mary."
tiara (n.): 1550s, "headdress of the Persian kings" (also worn by men of rank), from Latin tiara, from Greek tiara, of unknown origin. Earlier in anglicized form tiar (1510s).
Tib: 1530s, typical name for an English woman of the lower class, hence "girl, lass, sweetheart," sometimes also "strumpet," from the pet form of Isabel. Often paired with Tom, as Jill was with Jack.
Tibert: name of the cat in "Reynard the Fox" (late 15c.), hence used as a proper name for any cat, from Flemish and Dutch Tybert, Old French Tibert. Identified by Shakespeare with masc. proper name Tibalt, which is from Old French Thibauld, from Germanic *Theobald (see Theobald).
Tibet: said to be a corruption in Chinese or Arabic of Bod, indigenous name, of unknown origin. As an adjective in English, Tibetian is older (1747) but Tibetan (1822) is now the usual word.
tibia (n.): lower leg bone, 1726, from Latin tibia "shinbone," also "pipe, flute," in which sense it originally came into English (1540s). Of unknown origin. The Latin plural is tibiæ.
tic (n.): twitching of a facial muscle, 1822, often a shortening of tic douloureux "severe facial neuralgia," literally "painful twitch" (1800), from French tic "a twitching disease of horses" (early 17c.), of unknown origin. Klein suggests an imitative origin; French etymologists compare it to Italian ticchio "whim, caprice."
tic douloureux (n.): 1800, French, literally "painful twitching;" see tic.
tick (n.1): parasitic blood-sucking arachnid animal, Old English ticia, from West Germanic *tik- (cf. Middle Dutch teke, Dutch teek, Old High German zecho, German Zecke "tick"), of unknown origin. French tique (mid-15c.), Italian zecca are Germanic loan-words.
tick (n.2): mid-15c., "light touch or tap," probably from tick (v.) and cognate with Dutch tik, Middle High German zic, and perhaps echoic. Meaning "sound made by a clock" is probably first recorded 1540s; tick-tock is recorded from 1848.
tick (v.): early 13c., "to touch or pat," perhaps from an Old English verb corresponding to tick (n.2), and perhaps ultimately echoic. Cf. Old High German zeckon "to pluck," Dutch tikken "to pat," Norwegian tikke "touch lightly." Related: Ticked; ticking.

To tick (someone) off is from 1915, originally "to reprimand, scold." The verbal phrase tick off was in use in several senses at the time: as what a telegraph instrument does when it types out a message (1873), as what a clock does in marking the passage of time (1846), to enumerate on one's fingers (1899), and in accountancy, etc., "make a mark beside an item on a sheet with a pencil, etc.," often indicating a sale (by 1881). This might be the direct source of the phrase, perhaps via WWI military bureaucratic sense of being marked off from a list as "dismissed" or "ineligible." Meaning "to annoy" is recorded from 1975.
tick (n.3): "credit," 1640s, shortening of ticket (n.).
tick-tack-toe (n.): 1884, probably an extension of tick-tack (1580s), a form of backgammon, possibly from Middle French trictrac, perhaps imitative of the sound of tiles on the board.
ticker (n.): 1821, "something that ticks," from tick (2); slang meaning "heart" first recorded 1930. Ticker tape (1902) is from ticker "telegraphic device for recording stock market quotations, etc." (1883).
ticket (n.): 1520s, "short note or document," from a shortened form of Middle French etiquet "label, note," from Old French estiquette "a little note" (late 14c.), especially one affixed to a gate or wall as a public notice, from estiquer "to affix, stick on, attach," from Frankish *stikkan, cognate with Old English stician "to pierce" (see stick (v.)).

Meaning "card or piece of paper that gives its holder a right or privilege" is first recorded 1670s, probably developing from the sense of "certificate, license, permit." The political sense of "list of candidates put forward by a faction" has been used in American English since 1711. Meaning "official notification of offense" is from 1930; parking ticket first attested 1947. Big ticket item is from 1970. Slang the ticket "just the thing, what is expected" is recorded from 1838, perhaps with notion of a winning lottery ticket.
ticket (v.): 1610s, from ticket (n.). Related: Ticketed; ticketing.
ticking (n.): "cloth covering for mattresses or pillows," 1640s, from tyke (modern tick) with the same meaning (mid-14c.), probably from Middle Dutch tike, from a West Germanic borrowing of Latin theca "case," from Greek theke "a case, box, cover, sheath" (see theco-).
tickle (v.): early 14c. (intransitive) "to be thrilled or tingling," of uncertain origin, possibly a frequentative form of tick (2) in its older sense of "to touch." The Old English form was tinclian. Some suggest a metathesis of kittle (Middle English kytyllen), from Dutch kietelen, from a common North Sea Germanic word for "to tickle" (cf. Old Norse kitla, Old High German kizzilon, German kitzeln).

Meaning "to excite agreeably" (late 14c.) is a translation of Latin titillare. Meaning "to touch lightly so as to cause a peculiar and uneasy sensation" is recorded from late 14c.; that of "to poke or touch so as to excite laughter" is from early 15c.; figurative sense of "to excite, amuse" is attested from 1680s. Related: Tickled; tickling. The noun is recorded from 1801.
tickled (adj.): "pleased, happy," 1580s, past participle adjective from tickle (v.).
ticklish (adj.): "easily tickled," 1590s, from tickle + -ish. Literal sense is attested later than the figurative sense (1580s); an earlier word for this was tickly (1520s). Related: Ticklishly; ticklishness.
ticky-tacky (n.): "inferior, cheap material," 1962 (in song "Little Boxes" by U.S. political folk-singer Malvina Reynolds, 1900-1978), reduplication of tacky.
tidal (adj.): 1807, a hybrid formation from tide (n.) + Latin-derived suffix -al (1). A tidal wave (1830) is properly high water caused by movements of the tides; erroneous use for "tsunami, great ocean wave caused by an earthquake, etc." is recorded from 1878.
tidbit (n.): c.1640, probably from dialectal tid "fond, solicitous, tender" + bit (n.1) "morsel."
tiddlywinks (n.): children's tile-flipping game, 1857, probably an arbitrary formation from baby talk, but perhaps from slang tiddly-wink "unlicensed drink shop" (1844), from slang tiddly "a drink, drunk."
tide (n.): Old English tid "point or portion of time, due time," from Proto-Germanic *tidiz "division of time" (cf. Old Saxon tid, Dutch tijd, Old High German zit, German Zeit "time"), from PIE *di-ti- "division, division of time," suffixed form of root *da- "to divide, cut up" (cf. Sanskrit dati "cuts, divides;" Greek demos "people, land," perhaps literally "division of society;" daiesthai "to divide;" Old Irish dam "troop, company").

Meaning "rise and fall of the sea" (mid-14c.) is probably via notion of "fixed time," specifically "time of high water;" either a native evolution or from Middle Low German getide (cf. also Dutch tij, German Gezeiten "flood tide"). Old English seems to have had no specific word for this, using flod and ebba to refer to the rise and fall. Old English heahtid "high tide" meant "festival, high day."
tide (v.): "to carry (as the tide does)," 1620s, from tide (n.). Usually with over. Related: Tided; tiding.
tidings (n.): "announcement of an event," 1069, from Old English tidung "event, occurrence, piece of news," perhaps in part a verbal noun from Old English tidan "to happen," in part from Old Norse tiðendi (plural) "events, news," from tiðr (adj.) "occurring," from PIE *di-ti- (see tide (n.)). Cf. Norwegian tidende "tidings, news," Dutch tijding, German Zeitung "newspaper."
tidy (v.): "to make neat, set in order," 1821, from tidy (adj.). Related: Tidied; tidying.
tidy (adj.): mid-13c., probably originally "in season, timely, opportune, excellent," from tide in the sense of "season, time" (see tide). Cf. Old High German zitig, German zeitig, Dutch tijdig, Danish tidig "timely." Meaning "neat and in order" first recorded 1706.
tie (n.): "that with which anything is tied," Old English teag, from Proto-Germanic *taugo (cf. Old Norse taug "tie," tygill "string"), from PIE *deuk- "to pull, to lead" (cf. Old English teon "to draw, pull, drag;" see duke (n.)).

Figurative sense is recorded from 1550s. Meaning "equality between competitors" is first found 1670s, from notion of a connecting link (tie-breaker is recorded from 1961). Sense of "necktie, cravat" first recorded 1761. The railway sense of "transverse sleeper" is from 1857, American English.
tie (v.): Old English tigan, tiegan, from the source of tie (n.). Related: Tied; tying. Tie-dye first attested 1904. Tie one on "get drunk" is recorded from 1951. In the noun sense of "connection," tie-in dates from 1934.
tier (n.): "row, rank, range," 1560s, from Middle French tire, from Old French tire "rank, sequence, order" (early 13c.), probably from tirer "to draw, draw out" (see tirade). Some suggests the French noun is from a Germanic source akin to Old High German ziari, German Zier "adornment," Old English tir "glory, honor."
tierce (n.): old unit of measure equal to one-third of a pipe (42 gallons), 1530s, from Anglo-French ters, Old French tierce, from Latin tertia, fem. of tertius "a third," from root of tres "three" (see three). Also used in Middle English for "a third part" (late 15c.), "the third hour of the canonical day" (ending at 9 a.m.), late 14c., and, in astronomy and geometry, "sixtieth part of a second of an arc."
tiff (n.): 1727, "outburst of temper," later "small quarrel" (1754), of uncertain origin; OED suggests imitative, "from the sound of a slight puff of air or gas."
tiffany (n.): "type of thin, transparent fabric," c.1600; earlier a common name for the festival of the Epiphany (early 14c.; in Anglo-French from late 13c.), from Old French Tifinie, Tiphanie (c.1200), from Late Latin Theophania "Theophany," another name for the Epiphany, from Greek theophania "the manifestation of a god."

Also popular in Old French and Middle English as a name given to girls born on Epiphany Day. The fabric sense is found only in English and is of obscure origin and uncertain relation to the other meanings, unless as a fanciful allusion to "manifestation:"
The invention of that fine silke, Tiffanie, Sarcenet, and Cypres, which instead of apparell to cover and hide, shew women naked through them. [Holland's "Pliny," 1601]
The fashionable N.Y. jewelry firm Tiffany & Co. (1895) is named for its founder, goldsmith Charles L. Tiffany (1812-1902) and his son, Louis C. Tiffany (1848-1933), who was the Art Nouveau decorator noted for his glassware. The surname is attested in English from 1206.
tig (n.): child's game, 1816, variant of tag (n.2).
tiger (n.): Old English tigras (plural), also in part from Old French tigre (mid-12c.), both from Latin tigris "tiger," from Greek tigris, possibly from an Iranian source. The meaning "shriek or howl at the end of a cheer" is recorded from 1845, American English. Tiger's-eye "yellowish-brown quartz" is recorded from 1891.
tight (adj.): mid-15c., "dense, close, compact," from Middle English thight, from Old Norse þettr "watertight, close in texture, solid," from Proto-Germanic *thenkhtuz (cf. second element in Old English meteþiht "stout from eating;" Middle High German dihte "dense, thick," German dicht "dense, tight," Old High German gidigan, German gediegen "genuine, solid, worthy"), from PIE root *tenk- "to become firm, curdle, thicken" (cf. Irish techt "curdled, coagulated," Lithuanian tankus "close, tight," Persian tang "tight," Sanskrit tanakti "draws together, contracts").

Sense of "drawn, stretched" is from 1570s; meaning "fitting closely" (as of garments) is from 1779; that of "evenly matched" (of a contest, bargain, etc.) is from 1828, American English; that of "drunk" is from 1830; that of "close, sympathetic" is from 1956. Tight-assed "unwilling to relax" is attested from 1903. Tight-laced is recorded from 1741 in both the literal and figurative senses. Tight-lipped is first attested 1876.
tighten (v.): "to make tight," 1727; the earlier verb was simply tight, from Old English tyhtan, from the root of tight. Related: Tightened; tightening.
tightrope (n.): 1801, from tight (adj.) + rope (n.).
tights (n.): 1827, "tight-fitting breeches," from tight. Meaning "skin-tights worn by dancers, acrobats, etc." is attested from 1836.
tightwad (n.): "parsimonious person," 1900, from tight in the sense of "close-fisted" (1805) + wad (n.). The notions of stringency and avarice also combine in Modern Greek sphiktos "greedy," literally "tight."
tigress (n.): 1610s, from tiger + -ess.
Tijuana: from the name of a Diegueño (Yuman) village, written Tiajuan in 1829; deformed by folk-etymology association with Spanish Tia Juana "Aunt Jane."
Tiki (n.): "large wooden image of the creator-ancestor of Maoris and Polynesians," 1777, from Eastern Polynesian tiki "image." Tiki torch is first recorded 1973.
til: variant of till (prep.) or short for until.
tilapia (n.): 1849, formed in Modern Latin, perhaps from Greek tilon, name of a fish in Aristotle, + apios "distant."