trekker (n.) Look up trekker at Dictionary.com
"one who treks," 1851, agent noun from trek (v.).
trekkie (n.) Look up trekkie at Dictionary.com
1888, South African, "party of trekkers" (see trek). Meaning "fan of the television program 'Star Trek' " attested by 1976.
trellis (n.) Look up trellis at Dictionary.com
late 14c., "lattice, grating," from Old French trelis, trellis "trellis, fence," originally "sackcloth," from Vulgar Latin *trilicius, from Latin trilicis, genitive of trilix "having three threads, triple-twilled," from tri- (see tri-) + licium "thread."

Sense extended in Old French to things "woven" of iron, etc., which brought on influence of Old French treille "vine trellis," perhaps from Latin trichila "bower, arbor," which is apparently from Latin triclinium "couch extending round three sides of a table" (for reclining on at meals). Meaning "lattice used to support growing vines" is from 1510s. As a verb, c. 1400. Related: Trellised.
tremble (v.) Look up tremble at Dictionary.com
c. 1300, "shake from fear, cold, etc.," from Old French trembler "tremble, fear" (11c.), from Vulgar Latin *tremulare (source also of Italian tremolare, Spanish temblar), from Latin tremulus "trembling, shaking, quaking," from tremere "to tremble, shiver, quake," from PIE *trem- "to tremble" (source also of Greek tremein "to shiver, tremble, to quake, to fear," Lithuanian trimu "to chase away," Old Church Slavonic treso "to shake," Gothic þramstei "grasshopper"). A native word for this was Old English bifian. Related: Trembled; trembling. The noun is recorded from c. 1600.
tremblor (n.) Look up tremblor at Dictionary.com
"earthquake," 1913, alteration of temblor, by influence of trembler, agent noun of tremble (v.).
tremendous (adj.) Look up tremendous at Dictionary.com
1630s, "awful, dreadful, terrible," from Latin tremendus "fearful, to be dreaded, terrible," literally "to be trembled at," gerundive form of tremere "to tremble" (see tremble (v.)). Hyperbolic or intensive sense of "extraordinarily great or good, immense" is attested from 1812, paralleling semantic changes in terrific, terrible, dreadful, awful, etc. Related: Tremendously.
tremolo (n.) Look up tremolo at Dictionary.com
"tremulous effect in music," 1801, from Italian tremolo, from Latin tremulus "trembling" (see tremulous).
tremor (n.) Look up tremor at Dictionary.com
late 14c., "terror," from Old French tremor "fear, terror, quaking" (13c.), from Latin tremorem (nominative tremor) "a trembling, terror," from tremere (see tremble (v.)). Sense of "an involuntary shaking" first recorded 1610s and probably represents a re-introduction from Latin.
tremulous (adj.) Look up tremulous at Dictionary.com
1610s, from Latin tremulus "shaking, quivering," from tremere "to shake, quake, quiver" (see tremble (v.)). Related: Tremulously; tremulousness.
trench (n.) Look up trench at Dictionary.com
late 14c., "track cut through a wood," later "long, narrow ditch" (late 15c.), from Old French trenche "a slice, cut, gash, slash; defensive ditch" (13c., Modern French tranche), from trenchier "to cut, carve, slice," possibly from Vulgar Latin *trincare, from Latin truncare "to cut or lop off" (see truncate). Trenches for military protection are first so called c. 1500. Trench warfare first attested 1918. Trench-coat first recorded 1916, a type of coat worn by British officers in the trenches during World War I.
trenchant (adj.) Look up trenchant at Dictionary.com
early 14c., "cutting, sharp," from Old French trenchant "cutting, sharp" (literal and figurative), present participle of trenchier "to cut" (see trench). Figurative sense in English is from c. 1600.
trencher (n.) Look up trencher at Dictionary.com
"wooden platter on which to cut meat," c. 1300, from Anglo-French trenchour, Old North French trencheor "a trencher," literally "a cutting place," from Old French trenchier "to cut, carve, slice" (see trench).
trend (v.) Look up trend at Dictionary.com
1590s, "to run or bend in a certain direction" (of rivers, coasts, etc.), from Middle English trenden "to roll about, turn, revolve," from Old English trendan "turn round, revolve, roll," from Proto-Germanic *trandijan (source also of Old English trinde "round lump, ball," Old Frisian trind, Middle Low German trint "round," Middle Low German trent "ring, boundary," Dutch trent "circumference," Danish trind "round"); origin and connections outside Germanic uncertain. Sense of "have a general tendency" (used of events, opinions, etc.) is first recorded 1863, from the nautical sense. Related: Trended; trending.
trend (n.) Look up trend at Dictionary.com
"the way something bends" (coastline, mountain range, etc.), 1777, earlier "round bend of a stream" (1620s), from trend (v.); sense of "general course or direction" is from 1884. Sense of "a prevailing new tendency in popular fashion or culture" is from c. 1950.
trendsetter (n.) Look up trendsetter at Dictionary.com
also trend-setter, 1950, from trend (n.) + agent noun from set (v.). Related: Trend-setting.
trendy (adj.) Look up trendy at Dictionary.com
1962, from trend (n.) + -y (2). Related: Trendily; trendiness.
Trent Look up Trent at Dictionary.com
river in England, a Celtic name, perhaps "great wanderer," in reference to its flooding. The city in Italy (Italian Trento) is Roman Tridentum, in reference to the triple-peaked mountain nearby. The great ecumenical council there was held from 1543-63.
Trenton Look up Trenton at Dictionary.com
city in New Jersey, U.S., originally Trent's Town, from William Trent, Philadelphia merchant who laid it out in 1714.
trepan (v.) Look up trepan at Dictionary.com
c. 1400, from Old French trépaner (14c.), from trepan (n.), the name of the tool with which it was done, from Medieval Latin trepanum "a saw for cutting out small pieces of bone from the skull," from Greek trypanon "a borer, an auger, a carpenter's tool; a surgeon's trepan," from trypan "to bore," related to trype "hole" (cognate with Old Church Slavonic truplu "hollow"), from PIE *trup-, from root *tere- (1) "to rub, turn" (see throw (v.)). Related: Trepanned; trepanning.
trephine (n.) Look up trephine at Dictionary.com
an improved kind of trepan, 1620s, from French trephine, which is said to be from Latin tres fines "three ends," but perhaps rather an arbitrary diminutive of trepan. As a verb from 1804. Related: Trephining; trephination.
trepid (adj.) Look up trepid at Dictionary.com
"trembling from fear or terror," 1640s, from Latin trepidus "scared" (see trepidation). Related: Trepidly; trepidness.
trepidation (n.) Look up trepidation at Dictionary.com
c. 1600, from Middle French trepidation (15c.) and directly from Latin trepidationem (nominative trepidatio) "agitation, alarm, trembling," noun of action from past participle stem of trepidare "to tremble, hurry," from trepidus "alarmed, scared," from PIE *trep- (1) "to shake, tremble" (source also of Sanskrit trprah "hasty," Old Church Slavonic trepetati "to tremble"), related to *trem- (see tremble (v.)). Related: Trepidacious (1915).
tres (adv.) Look up tres at Dictionary.com
"very," 1815, from French très, from Old French tres "right, precisely, completely, very," from Latin trans "beyond" (see trans-), later "very" (compare Old Italian trafreddo "very cold").
trespass (v.) Look up trespass at Dictionary.com
c. 1300, "transgress in some active manner, commit an aggressive offense, to sin," from Old French trespasser "pass beyond or across, cross, traverse; infringe, violate," from tres- "beyond" (from Latin trans-; see trans-) + passer "go by, pass" (see pass (v.)). Meaning "enter unlawfully" is first attested in forest laws of Scottish Parliament (c. 1455). The Modern French descendant of Old French trespasser, trépasser, has come to be used euphemistically for "to die" (compare euphemistic use of cross over, and obituary). Related: Trespassed; trespassing.
trespass (n.) Look up trespass at Dictionary.com
c. 1300, "a transgression," from Old French trespas, verbal noun from trespasser (see trespass (v.)). Related: Trespasses.
tress (n.) Look up tress at Dictionary.com
c. 1300, "long lock of hair," from Old French tresse "a plait or braid of hair" (12c.), of uncertain origin, perhaps from Vulgar Latin *trichia "braid, rope," from Greek trikhia "rope," from thrix (genitive trikhos) "hair." Related: Tresses.
tress (v.) Look up tress at Dictionary.com
"arrange in tresses," mid-14c., from Old French trecier (12c.), from tresse (see tress (n.)).
tressel (n.) Look up tressel at Dictionary.com
see trestle.
trestle (n.) Look up trestle at Dictionary.com
early 14c., "a support for something," from Old French trestel "crossbeam" (12c., Modern French tréteu), presumed to be an alteration of Vulgar Latin *transtellum, diminutive of transtrum "beam, crossbar" (see transom). Specific meaning "support for a bridge" is recorded from 1796.
tret (n.) Look up tret at Dictionary.com
"allowance on goods sold by weight," c. 1500, of unknown origin; perhaps related to trait "act of drawing."
Trevor Look up Trevor at Dictionary.com
surname, from Trevor, Denbeigh.
trey (n.) Look up trey at Dictionary.com
late 14c., "card, die, or domino with three spots," from Anglo-French, Old French treis (Modern French trois), oblique case of treie "three," from Latin tria (neuter) "three" (see three). In slang use for "three (of anything)" from 1887.
tri- Look up tri- at Dictionary.com
word-forming element meaning "three, having three, once every three," from Latin tres (neuter tria) or Greek treis, trias "three" (see three).
triad (n.) Look up triad at Dictionary.com
1540s, "group or set of three," from Late Latin trias (genitive triadis), from Greek trias (genitive triados) "a triad, the number three," from treis "three" (see three). Musical sense of "chord of three notes" is from 1801. Related: Triadic.
triage (n.) Look up triage at Dictionary.com
1727, "action of assorting according to quality," from French triage "a picking out, sorting" (14c.), from Old French trier "to pick, cull" (see try (v.)). There seems to be some influence from or convergence with Latin tria "three" (as in triage for "coffee beans of the third or lowest quality"). In World War I, adopted for the sorting of wounded soldiers into groups according to the severity of their injuries, from French use.
First of all, the wounded man, or "blessé, is carried into the first of the so-called "Salles de Triage" or sorting wards. Here his name and regimental number, and if he is in condition to give it, the address of his family are taken; .... Then a hasty look-over from the surgeon sends him into one of the two other "Salles de Triage" -- that of the "Petits Blessés" if he is only slightly wounded and that of the "Grands Blessés" if he is more severely so. [Woods Hutchinson, M.D., "The Doctor in War," Boston, 1918]
trial (n.) Look up trial at Dictionary.com
mid-15c., "act or process of testing, a putting to proof by examination, experiment, etc.," from Anglo-French trial, noun formed from triet "to try" (see try (v.)). Sense of "examining and deciding of the issues between parties in a court of law" is first recorded 1570s; extended to any ordeal by 1590s. As an adjectival phrase, trial-and-error is recorded from 1806. Trial balloon (1826) translates French ballon d'essai, a small balloon sent up immediately before a manned ascent to determine the direction and tendency of winds in the upper air, though the earliest use in English is figurative.
triangle (n.) Look up triangle at Dictionary.com
late 14c., from Old French triangle (13c.), from Latin triangulum "triangle," noun use of neuter of adjective triangulus "three-cornered, having three angles," from tri- "three" (see tri-) + angulus "corner, angle" (see angle (n.)).
triangular (adj.) Look up triangular at Dictionary.com
c. 1400, from Late Latin triangularis "triangular, pertaining to a triangle," from Latin triangulus "with three corners" (the usual adjective in classical Latin), as a noun, "a triangle;" see triangle. Related: Triangularly.
In the huts of witches all the instruments and implements are triangular. ["Handwörterbuch des deutschen Aberglaubens"]
triangularity (n.) Look up triangularity at Dictionary.com
1680s, from triangular + -ity.
triangulate (v.) Look up triangulate at Dictionary.com
1833, originally in surveying, from Latin triangulum "a triangle" (see triangle) + -ate (2). Related: Triangulated; triangulating. Figurative use by 1860.
triangulation (n.) Look up triangulation at Dictionary.com
1809, from French triangulation, from Medieval Latin triangulationem (mid-12c., nominative triangulatio), noun of action from Latin *triangulare, from triangulum (see triangle).
triannual (adj.) Look up triannual at Dictionary.com
1630s, from tri- + annual (adj.). Related: Triannually.
Triassic (adj.) Look up Triassic at Dictionary.com
1841, from German, coined 1841 by German geologist Friedrich August von Alberti (1795-1878), from Trias "period preceding the Jurassic," from Greek trias "triad, the number three" (see triad). So called because it is divisible (in Germany) into three groups.
triathlete (n.) Look up triathlete at Dictionary.com
by 1983; see triathlon + athlete.
triathlon (n.) Look up triathlon at Dictionary.com
1970, from tri- "three" + Greek athlon "contest;" formed on model of decathlon, biathlon, etc. Originally of various combinations of events; one of the earliest so called combined clay-pigeon shooting, fly-fishing, and horse-jumping; another was cross-country skiing, target shooting, and a giant slalom run; and a third connected to the U.S. Army involved shooting, swimming, and running. Applied to the combination of a long swim, a bicycle-race, and a marathon by 1981.
triaxial (adj.) Look up triaxial at Dictionary.com
1886, from tri- + axial.
tribadism (n.) Look up tribadism at Dictionary.com
"lesbian sexual activity," 1811, with -ism + tribade (n.), c. 1600, "a lesbian," from French tribade (16c.) or directly from Latin tribas, from Greek tribas, from tribein "to rub, rub down, wear away," from PIE root *tere- (1) "to rub, turn, twist" (see throw (v.)). In reference to a specific sexual technique, from 1965.
tribal (adj.) Look up tribal at Dictionary.com
1630s, "pertaining to or characteristic of tribes," from tribe + -al (1). Meaning "characterized by a strong sense of loyalty to one's group" is from 1951 (Arendt). As a style of belly-dance from 1999, American English. Related: Tribally.
tribalism (n.) Look up tribalism at Dictionary.com
1868, "condition of being a tribe," from tribal + -ism. Meaning "group loyalty" attested by 1955.
tribe (n.) Look up tribe at Dictionary.com
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.