Online Etymology Dictionary

tribe (n.): mid-13c., "one of the twelve divisions of the ancient Hebrews," from Old French tribu or directly from Latin tribus "one of the three political/ethnic divisions of the original Roman state" (Tites, Ramnes, and Luceres, corresponding, perhaps, to the Latins, Sabines, and Etruscans), later, one of the 30 political divisions instituted by Servius Tullius (increased to 35 in 241 B.C.E.), of unknown origin. Perhaps from tri- "three" + *bheue-, root of the verb be. Others connect the word with the PIE root *treb- "a dwelling" (see tavern).

In the Biblical sense, which was the original one in English, the Latin word translates Greek phyle "race or tribe of men, body of men united by ties of blood and descent, a clan" (see phylo-). Extension to modern ethnic groups or races of people is from 1590s, specifically "a division of a barbarous race of people, usually distinguishable in some way from their congeners, united into a community under a recognized head or chief" [Century Dictionary], but colloquially of any aggregate of individuals of a kind.
TriBeCa: 1983, area in Manhattan between Broadway and the Hudson, south of Greenwich Village, from "triangle below Canal (Street)."
tribesman (n.): 1798, from genitive of tribe (n.) + man (n.).
tribology (n.): 1965, "study of friction," from comb. form of Greek tribos "rubbing," from tribein "to rub, rub down, wear away" (from PIE root *tere- (1) "to rub, turn, twist;" see throw (v.)) + -logy.
tribulation (n.): c. 1200, from Old French tribulacion (12c.), from Church Latin tribulationem (nominative tribulatio) "distress, trouble, affliction," noun of action from past participle stem of tribulare "to oppress, afflict," a figurative use by Christian writers of Latin tribulare "to press," also possibly "to thresh out grain," from tribulum "threshing sledge," from stem of terere "to rub" (see throw (v.)) + -bulum, suffix forming names of tools.
tribunal (n.): early 15c., "a judgement seat," from Old French tribunal "justice seat, judgement seat" (13c.) and directly from Latin tribunal "platform for the seat of magistrates, elevation, embankment," from tribunus "official in ancient Rome, magistrate," literally "head of a tribe" (see tribune). Hence, "a court of justice or judicial assembly" (1580s).
tribune (n.): late 14c., title of an official in ancient Rome, from Latin tribunus "magistrate" (specifically one of the officers appointed to protect the rights and interests of the plebeians from the patricians), originally "head of a tribe" (in the Roman sense), from tribus (see tribe). Also "raised platform" (1762), from Italian tribuna, from Medieval Latin tribuna, from Latin tribunal in its classical sense "platform for the seats of magistrates in ancient Rome."
tributary (adj.): late 14c., "paying tribute," from Latin tributarius "liable to tax or tribute," from tributum (see tribute).
tributary (n.): late 14c., "person, country, etc. owing obedience or paying tribute or a tax to a sovereign or another people," from Latin tributarius (see tributary (adj.)). Meaning "stream that flows into a larger body" is from 1822, from the adjective in this sense, which is recorded from 1610s.
tribute (n.): mid-14c., "stated sum of money or other valuable consideration paid by one ruler or country to another in acknowledgment of submission or as the price of peace or protection," from Anglo-French tribute, Old French tribut and directly from Latin tributum "tribute, a stated payment, a thing contributed or paid," noun use of neuter of tributus, past participle of tribuere "to pay, assign, grant," also "allot among the tribes or to a tribe," from tribus (see tribe). Sense of "offering, gift, token" is first recorded 1580s.
trice (v.): late 14c., "haul up and fasten with a rope," from Middle Dutch trisen "hoist," from trise "pulley," of unknown origin. Hence at a tryse (mid-15c.) "in a very short time," literally "at a single pluck or pull." The Middle Dutch word is the source of Dutch trijsen "to hoist" and is cognate with Middle Low German trissen (source of Danish trisse, German triezen); its further etymology is unknown.
triceps (n.): the great extensor muscle, 1704, from Latin triceps "three-headed," from tri- "three" (see tri-) + -ceps, from caput "head" (see capitulum). So called because the muscle has three origins.
triceratops (n.): dinosaur genus, 1890, from Greek trikeratos "three-horned" + ops "face," literally "eye," from PIE *okw- "to see" (see eye (n.)). The first element is from tri- "three" (see three) + keras (genitive keratos) "horn of an animal," from PIE *ker- (1) "horn, head" (see horn (n.)).
trichinosis (n.): "disease caused by trichinae," 1864, coined by Bernhard Rupprecht (1815-1877) by 1864 from trichina (1835), Modern Latin, genus name of the minute, hair-like parasitic worms that cause it, from Greek trikhine, fem. of trikhinos "of or like hair," from thrix (genitive trikhos) "hair."
trichomoniasis (n.): 1915, with -iasis + trichomonas, genus of a family of flagellate parasites, from tricho-, Latinized form of Greek trikho-, comb. form of thrix (genitive trikhos) "hair" + -monas.
trichotillomania (n.): 1905, from French trichotillomanie (1889), from tricho-, Latinized form of Greek trikho-, comb. form of thrix (genitive trikhos) "hair" + Greek tillesthai "to pull out" + mania.
trick (n.): early 15c., "a cheat, a mean ruse," from Old North French trique "trick, deceit, treachery, cheating," from trikier "to deceive, to cheat," variant of Old French trichier "to cheat, trick, deceive," of uncertain origin, probably from Vulgar Latin *triccare, from Latin tricari "be evasive, shuffle," from tricæ "trifles, nonsense, a tangle of difficulties," of unknown origin.

Meaning "a roguish prank" is recorded from 1580s; sense of "the art of doing something" is first attested 1610s. Meaning "prostitute's client" is first attested 1915; earlier it was U.S. slang for "a robbery" (1865). To do the trick "accomplish one's purpose" is from 1812; to miss a trick "fail to take advantage of opportunity" is from 1889; from 1872 in reference to playing the card-game of whist, which might be the original literal sense. Trick-or-treat is recorded from 1942. Trick question is from 1907.
trick (v.): "deceive by trickery," 1590s, from trick (n.). Related: Tricked; tricking. The sense of "to dress, adorn" (c. 1500) is perhaps a different word entirely.
trickery (n.): 1719, from trick (v.) + -ery.
trickle (v.): late 14c., intransitive, of uncertain origin, possibly a shortened variant of stricklen "to trickle," a frequentative form of striken "to flow, move" (see strike (v.)). Transitive sense from c. 1600. Related: Trickled; trickling. Trickle-down as an adjectival phrase in an economic sense first recorded 1944; the image had been in use at least since Teddy Roosevelt.
trickle (n.): 1570s, from trickle (v.).
trickster (n.): 1711, from trick (n.) + -ster.
tricky (adj.): 1786, "characterized by tricks," from trick (n.) + -y (2). Meaning "deceptively difficult" is from 1868. Related: Trickily; trickiness. Earlier was tricksy (1590s).
tricolor (n.): also tricolour, 1798, "flag having three colors," especially the emblem of France adopted during the Revolution, from French tricolore, in drapeau tricolore "three-colored flag." The arrangement of colors on the modern French national flag dates from 1794.
tricot (n.): knitted fabric, 1859, from French tricot "knitting, knitted work," from tricoter "to knit," of uncertain origin, probably a variant of Old French estriquer "to smooth," from a Germanic source (such as Middle Low German striken "pass over lightly").
tricuspid (n.): 1660s, from Latin tricuspidem (nominative tricuspis) "three-pointed," from tri- (see tri-) + cuspis "point" (see cusp).
tricycle (n.): 1828, "three-wheeled horse-drawn carriage," from French tricycle (1827); see tri- + cycle (n.). The pedal-powered version is first attested 1868.
trident (n.): "three-pointed spear," mid-15c., from Latin noun use of adjective tridentem (nominative tridens) "three-pronged, three-toothed," from tri- "three" (see tri-) + dens "tooth" (see tooth). As a type of U.S. nuclear-powered submarine, recorded from 1972. Related: Tridental.
tried (adj.): "tested, proven, trusty," mid-14c., past participle adjective from try (v.). Coupled since mid-14c. with true.
triennial (adj.): 1630s, "lasting three years;" 1640s, "occurring every three years," with -al (1) + Latin triennium "three-year period," from tri- "three" (see tri-) + annus "year" (see annual). For vowel change, see biennial. As a noun, 1630s. Related: Triennially.
Trier: city in Germany (French Trèves), founded c. 15 B.C.E. by Augustus, named for the indigenous Gaulish people, the Treveri.
trifecta (n.): 1974, from tri- + perfecta.
trifid (adj.): "divided into three lobes," 1620s, from Latin trifidus "cleft in three," from tri- "three" (see tri-) + -fid. This adjective probably inspired triffid, the name of the three-legged walking poisonous plants in John Wyndham's novel "The Day of the Triffids" (1951).
trifle (n.): c. 1200, trufle "false or idle tale," later "matter of little importance" (c. 1300), from Old French trufle "mockery," diminutive of truffe "deception," of uncertain origin. As a type of light confection from 1755.
trifle (v.): "treat lightly," 1520s, from trifle (n.). Earlier "cheat, mock" (c. 1300). Related: Trifled; trifling.
trifocals (n.): 1899, from bifocals with tri-.
trig (adj.): "smart, trim," c. 1200, from Old Norse tryggr "firm, trusty, true," from Proto-Germanic *treuwaz- (see true (adj.)). A Scottish and northern word only until 19c. Related: Trigness.
trig (n.): 1895 as a shortening of trigonometry.
trigeminal (adj.): 1815, from Latin trigeminus "born in threes," as a noun, "triplets;" from tri- (see tri-) + geminus "born at the same birth" (see geminate (adj.)).
trigger (n.): "device by means of which a catch or spring is released and a mechanism set in action," 1650s, earlier tricker (1620s), from Dutch trekker "trigger," from trekken "to pull" (see trek). Tricker was the usual form in English until c. 1750. Trigger-happy is attested from 1942.
trigger (v.): 1930, from trigger (n.). Related: Triggered; triggering.
triglyceride (n.): 1860, malformed from tri- + glyceride. So called for the three radicals which replace the three hydrogen atoms.
trigonometric (adj.): 1811; see trigonometry + -ic. Related: Trigonometrical (1660s).
trigonometry (n.): "branch of mathematics that deals with relations between sides and angles of triangles," 1610s, from Modern Latin trigonometria (Barthelemi Pitiscus, 1595), from Greek trigonon "triangle" (from tri- "three" (see tri-) + gonia "angle" (see -gon)) + metron "a measure" (see meter (n.2)).
trike (n.): short for tricycle, 1883.
trilateral (adj.): 1650s, from Late Latin trilaterus "three-sided;" see tri- + lateral. The Trilateral Commission (representing Japan, the U.S., and Europe) was founded 1973. Related: Trilateralism; trilaterally.
trilby (n.): type of hat, 1897, from name of Trilby O'Ferrall, eponymous heroine of the novel by George du Maurier (1834-1896), published in 1894. In the stage version of the novel, the character wore this type of soft felt hat. In plural, also slang for "feet" (1895), in reference to the eroticism attached in the novel to the heroine's bare feet. Related: Trilbies.
trilemma (n.): 1670s, from dilemma + tri-.
trilingual (adj.): "involving three languages," 1834, from tri- + Latin lingua "language," literally "tongue" (see lingual). Latin trilinguis meant "triple-tongued," and was used of Cerberus.
trill (n.): 1640s, from Italian trillio, triglio "a quavering or warbling in singing," probably ultimately of imitative origin. The verb is 1660s, from Italian trillare "to quaver, trill." Related: Trilled; trilling.