Online Etymology Dictionary

troublous (adj.): early 15c., from Old French troblos, torblos, from truble/torble (see trouble (n.)).
trough (n.): Old English trog "wooden vessel, tray, hollow vessel, canoe," from Proto-Germanic *trugaz (source also of Old Frisian, Old Saxon, Old Norse trog, Middle Dutch troch, Dutch trog, Old High German troc, German trog), from PIE *dru-ko-, from root *dru-, *deru- "wood, tree" (see tree (n.)). Originally pronounced in English with a hard -gh- (as in Scottish loch); pronunciation shifted to "-ff," but spelling remained.
trounce (v.): 1550s, "to trouble, afflict, harass," later "to beat, thrash" (1560s), of uncertain origin. Perhaps related to Middle French troncer "to cut, cut off a piece from," from tronce "piece of timber," from Old French tronc (see trunk (n.1)). Related: Trounced; trouncing.
troupe (n.): 1825, "company, band," especially of performers, actors, dancers, etc., from French troupe "company" (see troop (n.)).
trouper (n.): 1890, "actor or performer in a troupe," from troupe (n.) + -er (1). Transferred sense of "reliable, uncomplaining person" [OED] is attested by 1942, American English.
trousers (n.): "garment for men, covering the lower body and each leg separately," 1610s, earlier trouzes (1580s), extended from trouse (1570s), with plural ending typical of things in pairs, from Gaelic or Middle Irish triubhas "close-fitting shorts," of uncertain origin. Early recorded use of the word indicates the garment was regarded as Celtic: "A jellous wife was like an Irish trouze, alwayes close to a mans tayle" [1630]. The unexplained intrusive second -r- is perhaps by influence of drawers or other words in pairs ending in -ers.
trousseau (n.): "a bride's clothing, etc., brought from her former home," 1817, from French trousseau, originally "a bundle," diminutive of Old French trousse "bundle" (see truss (n.)). Italicized as foreign at first, nativized by 1833. The Old French word was borrowed into Middle English early 13c. as "a bundle of keys," but it fell from use.
trout (n.): Old English truht "trout," in part from Old French truite, both from Late Latin tructa, perhaps from Greek troktes "a kind of sea fish," literally "nibbler," from trogein "to gnaw," from PIE *tro-, from root *tere- (1) "to rub" (see throw (v.)). In late 17c. slang, trusty trout was used in a sense of "confidential friend."
trove (n.): 1888, from treasure trove (c. 1550), from Anglo-French tresor trové (late 12c.), translating Latin thesaurus inventus, literally "treasure found." Originally any precious metal object one finds hidden whose owner is unknown. As this usually meant ancient hoards, the term came to mean "treasure hoard" in popular use. Rendered treasure found from mid-15c. French trove is past participle of trover "to find," from Old French trover, torver, of unknown origin, perhaps from Latin turbare "to move" (hence "to seek for") or Medieval Latin *tropare "to compose, sing."
trow (v.): Old English treowan "to trust in, believe, hope, be confident; persuade, suggest; make true; be faithful (to), confederate with," from treow "faith, belief," from Proto-Germanic *treuwaz- (source also of Old Saxon truon, Old Frisian trouwa, Dutch vertrouwen "trust," Old High German triuwen, German trauen "hope, believe, trust;" see true (adj.)).
trowel (n.): mid-14c., "tool for spreading plaster or mortar," from Old French truele "trowel" (13c.), from Late Latin truella "small ladle, dipper" (mid-12c.), diminutive of Latin trua "a stirring spoon, ladle, skimmer." The gardening tool was so called since 1796.
troy: late 14c., standard system of weights for gems and precious metals, from Troyes, city in France (Roman (Civitas) Tricassium, capital of the Tricasses, a Celtic people whose name was said to mean "those with three tresses"), former site of an important fair at which this weight is said to have been used. Many medieval towns had their own standard weights. The pound troy contains 5,760 grains and is divided into 12 ounces.
truancy (n.): 1754, from truant + -cy.
truant (n.): c. 1200, "beggar, vagabond," from Old French truant "beggar, rogue" (12c.), as an adjective, "wretched, miserable, of low caste," from Gaulish *trougant- (compare Breton *truan, later truant "vagabond," Welsh truan "wretch," Gaelic truaghan "wretched"), of uncertain origin. Compare Spanish truhan "buffoon," from same source. Meaning "one who wanders from an appointed place," especially "a child who stays away from school without leave" is first attested mid-15c.
truant (adj.): "idle, loitering, given to shirking duty or business," 1540s, from truant (n.).
truce (n.): "mutually agreed-upon temporary intermission of hostilities," early 13c., triws, variant of trewes, originally plural of trewe "faith, assurance of faith, covenant, treaty," from Old English treow "faith, truth, fidelity; pledge, promise, agreement, treaty," from Proto-Germanic *treuwaz- (source also of Old Frisian triuwe, Middle Dutch trouwe, Dutch trouw, Old High German triuwa, German treue, Gothic triggwa "faith, faithfulness"). Related to Old English treowe "faithful" (see true (adj.)). The Germanic word was borrowed into Late Latin as tregua, hence French trève, Italian tregua.
trucial (adj.): 1876, from truce + -ial. Trucial States, the pre-1971 name of the United Arab Emirates, is attested from 1891, in reference to the 1835 maritime truce between Britain and the Arab sheiks of Oman.
truck (n.1): "vehicle," 1610s, originally "small wheel" (especially one on which the carriages of a ship's guns were mounted), probably from Latin trochus "iron hoop," from Greek trokhos "wheel," from trekhein "to run" (see truckle (n.)). Sense extended to "cart for carrying heavy loads" (1774), then in American English to "motor vehicle for carrying heavy loads" (1913), a shortened form of motor truck in this sense (1901).
There have also been lost to the enemy 6,200 guns, 2,550 tanks and 70,000 trucks, which is the American name for lorries, and which, I understand, has been adopted by the combined staffs in North-West Africa in exchange for the use of the word petrol in place of gasolene. [Winston Churchill, address to joint session of U.S. Congress, May 19, 1943]
Truck stop is attested from 1956.
truck (v.1): "to exchange, barter," early 13c., from Old North French troquer "to barter, exchange," from Medieval Latin trocare "barter," of unknown origin. Rare before 16c. Sense of "have dealings with" is first recorded 1610s. The noun is first recorded 1550s, "act or practice of barter." Sense of "vegetables raised for market" is from 1784, preserved in truck farm (1866).
truck (v.2): "to convey on a truck," 1809, from truck (n.). Verbal meaning "dance, move in a cool way," first attested 1935, from popular dance of that name in U.S., supposedly introduced at Cotton Club, 1933. Related: Trucked; trucking.
truck (n.2): 1530s, "act or practice of barter, trading by exchange," from French troque, from troquer (see truck (v.1)). Sense of "dealings" is from 1620s. "Exchange of commodities, barter," then "commodities for barter and exchange." In this sense the word was given a wide use in 19c. American English: "Truck at first meant market-garden produce; then it came to mean stuff in general, including 'doctor-stuff.' SPUN TRUCK is knitting work" [Thornton, "American Glossary," 1912]. Sense of "vegetables raised for market" is from 1784, preserved in truck farm (1866).
trucker (n.): 1853, "worker who moves loads using a cart;" agent noun from truck (v.2). Meaning "person who drives a motorized truck" is by 1935, a shortening of truck driver (1907).
truckle (n.): "small wheel or roller," late 14c., from Anglo-French trocle, from Latin trochlea "a small wheel, sheaf of a pulley," from Greek trokhileia "a system of pulleys," from trokhos "wheel," from trekhein "to run," from PIE root *dhregh- "to run" (source also of Old Irish droch "wheel," Lithuanian pa-drosti "to run fast"). Truckle bed "small bed on wheels that can be stowed under a larger bed" is from mid-15c.
truckle (v.): "give up or submit tamely," 1610s, originally "sleep in a truckle bed" (see truckle (n.)). Meaning "give precedence, assume a submissive position" (1650s, implied in truckling) is perhaps in reference to that type of bed being used by servants and inferiors or simply occupying the lower position. Related: Truckled; truckling.
truculence (n.): 1727, from Latin truculentia "savageness, cruelty," from truculentus (see truculent). Related: Truculency (1560s).
truculent (adj.): 1530s, from Latin truculentus "fierce, savage, stern, harsh, cruel," from trux (genitive trucis) "fierce, rough, savage, wild." Related: Truculently.
trudge (v.): "to walk laboriously," 1540s, of unknown origin. Related: Trudged; trudging. The noun meaning "an act of trudging" is attested from 1835.
true (adj.): Old English triewe (West Saxon), treowe (Mercian) "faithful, trustworthy, honest, steady in adhering to promises, friends, etc.," from Proto-Germanic *treuwaz- "having or characterized by good faith" (source also of Old Frisian triuwi, Dutch getrouw, Old High German gatriuwu, German treu, Old Norse tryggr, Danish tryg, Gothic triggws "faithful, trusty"), from PIE *drew-o-, a suffixed form of the root *deru-/*dreu- "be firm, solid, steadfast" (source also of Lithuanian drutas "firm," Welsh drud, Old Irish dron "strong," Welsh derw "true," Old Irish derb "sure"), with specialized sense "wood, tree" and derivatives referring to objects made of wood (see tree (n.)).

Sense of "consistent with fact" first recorded c. 1200; that of "real, genuine, not counterfeit" is from late 14c.; that of "conformable to a certain standard" (as true north) is from c. 1550. Of artifacts, "accurately fitted or shaped" it is recorded from late 15c. True-love (n.) is Old English treowlufu. True-born (adj.) first attested 1590s. True-false (adj.) as a type of test question is recorded from 1923. To come true (of dreams, etc.) is from 1819.
true (v.): "make true in position, form, or adjustment," 1841, from true (adj.) in the sense "agreeing with a certain standard." Related: Trued; truing.
truffle (n.): type of edible underground fungus, 1590s, from Middle French trufle (14c.), probably from Old Provençal trufa, metathesized from Late Latin tufera (plural), cognate of Latin tuber "edible root." Another theory notes Italian tartuffo (Milanese tartuffel) "potato," supposedly from terræ tuber. Extended 1926 to powdered, round chocolates that look like truffles.
truism (n.): "self-evident truth," 1708, from true (adj.) + -ism; first attested in Swift.
trull (n.): "a low prostitute or concubine; a drab, strumpet, trollop" [OED], 1510s, from German trulle "trollop, wench, hussy," perhaps cognate with troll (n.), or perhaps from troll (v.), compare Middle High German trolle "awkward fellow," Swabian trull "a thick, fat woman."
truly (adv.): Old English treowlice, from treow (see true (adj.)). Similar formation in Dutch treuwelijk, German getreulich, Swedish troligen.
Truman: surname, attested by 1215, literally "faithful man, trusty man."
trumeau (n.): 1883, in architecture, "piece of a wall between two openings," as the central pillar of a great doorway," from French trumeau, literally "calf of the leg" (12c.), from a Germanic source (compare German Trumm "end, stump," Swedish dialectal tromm "stump, end of a log").
trump (n.1): "playing card of a suit ranking above others," 1520s, alteration of triumph (n.), which also was the name of a card game.
trump (v.2): "fabricate, devise," 1690s, from trump "deceive, cheat" (1510s), from Middle English trumpen (late 14c.), from Old French tromper "to deceive," of uncertain origin. Apparently from se tromper de "to mock," from Old French tromper "to blow a trumpet." Brachet explains this as "to play the horn, alluding to quacks and mountebanks, who attracted the public by blowing a horn, and then cheated them into buying ...." The Hindley Old French dictionary has baillier la trompe "blow the trumpet" as "act the fool," and Donkin connects it rather to trombe "waterspout," on the notion of turning (someone) around. Connection with triumph also has been proposed. Related: Trumped; trumping. Trumped up "false, concocted" first recorded 1728.
trump (n.2): "trumpet," c. 1300, from Old French trompe "long, tube-like musical wind instrument" (12c.), cognate with Provençal tromba, Italian tromba, all probably from a Germanic source (compare Old High German trumpa, Old Norse trumba "trumpet"), of imitative origin.
trump (v.1): "surpass, beat," 1580s, from trump (n.). Related: Trumped; trumping.
trumpery (n.): mid-15c., "deceit, trickery," from Middle French tromperie (14c.), from tromper "to deceive," of uncertain origin (see trump (v.2), which has influenced the spelling in English). Meaning "showy but worthless finery" is first recorded c. 1600.
trumpet (n.): late 14c., from Old French trompette "trumpet," diminutive of trompe (see trump (n.2)).
trumpet (v.): 1520s, from trumpet (n.). Figurative sense of "to proclaim, extol" is attested from 1580s. Related: Trumpeted; trumpeting.
truncate (v.): late 15c., from Latin truncatus "cut off," past participle of truncare "to maim, mutilate, cut off," from truncus "mutilated, cut off, deprived of branches or limbs" (see trunk (n.1)). Related: Truncated; truncating.
truncated (adj.): late 15c., past participle adjective from truncate. Originally in heraldry; modern senses are post-1700.
truncation (n.): early 15c., from Late Latin truncationem (nominative truncatio ), noun of action from past participle stem of truncare (see truncate).
truncheon (n.): c. 1300, "shaft of a spear," also "short stick, cudgel," from Old North French tronchon, Old French tronchon (11c., Modern French tronçon) "a piece cut off, thick stick, stump," from Vulgar Latin *truncionem (nominative *truncio), from Latin truncus "trunk of a tree" (see trunk (n.1)). Meaning "staff as a symbol of office" is recorded from 1570s; sense of "policeman's club" is recorded from 1816.
trundle (n.): "small wheel to support heavy weights," 1540s (implied in trundle bed "low bed on small wheels"), possibly from Middle English trendle "wheel, suspended hoop" (early 14c.), from Old English trendel "ring, disk" (see trend (v.)). Also probably in part from Old French trondeler "to roll down, fall down," which is of Germanic origin.
trundle (v.): 1590s (transitive), from trundle (n.). Intransitive use from 1620s. Related: Trundled; trundling.
trunk (n.1): mid-15c., "box, case," from Old French tronc "alms box in a church," also "trunk of a tree, trunk of the human body, wooden block" (12c.), from Latin truncus "trunk of a tree, trunk of the body," of uncertain origin, perhaps originally "mutilated, cut off." The meaning "box, case" is likely to be from the notion of the body as the "case" of the organs. English acquired the "main stem of a tree" and "torso of the body" senses from Old French in late 15c. The sense of "luggage compartment of a motor vehicle" is from 1930. Railroad trunk line is attested from 1843; telephone version is from 1889.
trunk (n.2): "elephant's snout," 1560s, apparently from trunk (n.1), perhaps from confusion with trump (n.2), short for trumpet.