tappet (n.) Look up tappet at Dictionary.com
machine part, 1745, apparently from tap (v.1) + -et, "but the use of the suffix is abnormal" [OED].
taproom (n.) Look up taproom at Dictionary.com
also tap-room, 1807, from tap (n.1) + room (n.).
taproot (n.) Look up taproot at Dictionary.com
c. 1600, from tap (n.) + root (n.).
taps (n.) Look up taps at Dictionary.com
U.S. military signal for lights out in soldiers' quarters (played 15 minutes after tattoo), 1824, from tap (v.), on the notion of drum taps (it originally was played on a drum, later on a bugle). As a soldier's last farewell, played over his grave, it may date to the American Civil War. The tune was revised several times in mid-19c.
tapster (n.) Look up tapster at Dictionary.com
"person employed to tap liquors," Old English tæppestre "female tavern-keeper, hostess at an inn, woman employed to tap liquors," fem of tæppere, from tæppa "tap" (see tap (n.1)) + fem. ending -ster. The distinction of gender in the word was lost by 15c., and by 1630s re-feminized tapstress is attested.
tar (n.1) Look up tar at Dictionary.com
a viscous liquid, Old English teoru, teru "tar, bitumen, resin, gum," literally "the pitch of (certain kinds of) trees," from Proto-Germanic *terwo- (cognates: Old Norse tjara, Old Frisian tera, Middle Dutch tar, Dutch teer, German Teer), probably a derivation of *trewo-, from PIE *derw-, variant of root *deru-, *dreu- in its sense "wood, tree" (see tree (n.)).

Tar baby "a sticky problem," also a derogatory term for "black person," is from an 1881 "Uncle Remus" story by Joel Chandler Harris. Tarheel for "North Carolina resident" first recorded 1864, probably from the gummy resin of pine woods. Tar water, an infusion of tar in cold water, was popular as a remedy from c. 1740 through late 18c.
tar (n.2) Look up tar at Dictionary.com
also Jack Tar, "sailor," 1670s, probably a special use of tar (n.1), which stuff was a staple for waterproofing aboard old ships (sailors also being jocularly called knights of the tarbrush); or possibly a shortened form of tarpaulin, which was recorded as a nickname for a sailor in 1640s, from the tarpaulin garments they wore.
tar (v.) Look up tar at Dictionary.com
late Old English, "to smear with tar," from tar (n.1). To tar and feather (1769) was famously a mob action in America in Revolutionary times (used by both sides) and several decades thereafter. The punishment itself first is found in an ordinance of Richard I (1189) as the penalty in the Crusader navy for theft. Among other applications over the years was its use in 1623 by a bishop on "a party of incontinent friars and nuns" [OED], but the verbal phrase is not attested until 18c. Related: Tarred; tarring.
tarantella (n.) Look up tarantella at Dictionary.com
1782, "peasant dance popular in Italy," originally "hysterical malady characterized by extreme impulse to dance" (1630s), epidemic in Apulia and adjacent parts of southern Italy 15c.-17c., popularly attributed to (or believed to be a cure for) the bite of the tarantula. This is likely folk-etymology, however, and the names of the dance and the spider more probably share an origin in Taranto, the name of a city in southern Italy (see tarantula). Used from 1833 to mean the style of music that accompanies this dance, usually in 6/8 time, with whirling triplets and abrupt major-minor modulations. Related: Tarantism.
tarantula (n.) Look up tarantula at Dictionary.com
1560s, "wolf spider," (Lycos tarantula), from Medieval Latin tarantula, from Italian tarantola, from Taranto "Taranto," seaport city in southern Italy in the region where the spiders are frequently found, from Latin Tarentum, from Greek Taras (genitive Tarantos; perhaps from Illyrian darandos "oak"). Its bite is only slightly poisonous. Popularly applied to other great hairy spiders, especially the genus Mygale, native to the warmer regions of the Americas (first so called in 1794).
tarbrush (n.) Look up tarbrush at Dictionary.com
1711, from tar (n.1) + brush (n.1). To have a touch of the tarbrush "have a dash of African ancestry visible in the skin tone" (1796) was "a term of contempt from the West Indies" [Century Dictionary].
tardation (n.) Look up tardation at Dictionary.com
"slowness," c. 1500, from Late Latin tardationem (nominative tardatio), noun of action from past participle stem of tardare "to slow," related to tardus "slow, sluggish" (see tardy).
tardigrade (adj.) Look up tardigrade at Dictionary.com
1620s, "slow-going, slow-moving," from French tardigrade (17c.), from Latin tardigradus "slow-paced," from tardus "slow" (see tardy) + gradi "to walk, go, step" (see grade (n.)).
tardy (adj.) Look up tardy at Dictionary.com
1520s, "slow," from Old French tardif "slow, late" (12c.), also the name of the snail character in the Roman de Renart, from Vulgar Latin *tardivus, from Latin tardus "slow, sluggish; late; dull, stupid," of unknown origin. Meaning "late" in English is from 1660s.
This word, not much used in English prose, is constantly employed in the U.S. and in Canada with reference to lateness in school-attendance. [Thornton, "American Glossary," 1912]
Related: Tardily; tardiness. Earlier form of the word in English was tardif, tardyve (late 15c.). Tardity "slowness of movement or action" is recorded in English from early 15c., from Old French tardete, from Latin tarditas.
tare (n.1) Look up tare at Dictionary.com
"kind of fodder plant, vetch," c. 1300, perhaps cognate with or from Middle Dutch tarwe "wheat," from a Germanic source perhaps related to Breton draok, Welsh drewg "darnel," Sanskrit durva "a kind of millet grass," Greek darata, daratos "bread," Lithuanian dirva "a wheat-field." Used in 2nd Wyclif version (1388) of Matt. xxiii:25 to render Greek zizania as a weed among corn (earlier darnel and cockle had been used in this place); hence figurative use for "something noxious sown among something good" (1711).
tare (n.2) Look up tare at Dictionary.com
"allowable difference between gross and net weight, deduction made from gross weight of goods to account for approximate weight of packaging or container holding them," late 15c., from Middle French tare "wastage in goods, deficiency, imperfection" (15c.), from Italian tara, Medieval Latin tara, from Arabic tarah, literally "thing deducted or rejected, that which is thrown away," from taraha "to reject."
targe (n.) Look up targe at Dictionary.com
"shield, buckler," late Old English, from Old French targe, from Frankish *targa, from Germanic (see target (n.)). Old English had a native form targe, but the soft -g- in the later word indicates it came from French.
target (n.) Look up target at Dictionary.com
c. 1300, "shield," diminutive of late Old English targe, from Old French targe "light shield" (12c.), from Frankish *targa "shield," from Proto-Germanic *targ- (cognates: Old High German zarga "edging, border," German zarge "border, edge, frame," Old English targe, Old Norse targa "shield, buckler"), perhaps originally "edge of a shield." Meaning "round object to be aimed at in shooting" first recorded 1757, originally in archery, perhaps suggested by the concentric circles in both. Target-practice is from 1801. Target audience is by 1951; early reference is to Cold War psychological warfare.
target (v.) Look up target at Dictionary.com
"to use as a target," 1837, from target (n.). Earlier it meant "to shield" (1610s). Related: Targeted; targeting.
tariff (n.) Look up tariff at Dictionary.com
1590s, "arithmetical table," also "official list of customs duties on imports or exports; law regulating import duties," from Italian tariffa "tariff, price, assessment," Medieval Latin tarifa "list of prices, book of rates," from Arabic ta'rif "information, notification, a making known; inventory of fees to be paid," verbal noun from arafa "he made known, he taught." Sense of "classified list of charges made in a business" is recorded from 1757. The U.S. Tariff of Abominations was passed in 1828.
tarmac (n.) Look up tarmac at Dictionary.com
1903, Tarmac, a trademark name, short for tarmacadam (1882) "pavement created by spraying tar over crushed stone," from tar (n.1) + John L. McAdam (see macadam). By 1919, tarmac was being used generally in Great Britain for "runway."
tarn (n.) Look up tarn at Dictionary.com
late 14c., mid-13c. in Anglo-Latin, from Old Norse tjörn "small mountain lake without visible tributaries," from Proto-Germanic *terno, perhaps originally "water hole" [Barnhart]. A dialectal word popularized by the Lake poets.
tarnation (n.) Look up tarnation at Dictionary.com
1784, American English alteration of darnation (itself a euphemism for damnation), influenced by tarnal (1790), a mild profanity, clipped from phrase by the Eternal (God) (see eternal).
tarnish (v.) Look up tarnish at Dictionary.com
mid-15c. (transitive), from present participle stem of Middle French ternir "dull the luster or brightness of, make dim" (15c.), probably from Old French terne (adj.) "dull, dark," which according to Diez is from a Germanic source cognate with Old High German tarnjan "to conceal, hide," Old English dyrnan "to hide, darken," from Proto-Germanic *darnjaz (see dern), but there are difficulties of form, sense, and date. Intransitive sense from 1670s. Figurative sense is from 1690s. Related: Tarnished; tarnishing.
tarnish (n.) Look up tarnish at Dictionary.com
1713, from tarnish (v.).
taro (n.) Look up taro at Dictionary.com
tropical food plant, 1769, from Polynesian (Tahitian or Maori) taro. Compare Hawaiian kalo.
taroc (n.) Look up taroc at Dictionary.com
1610s, name of an old card game of Italy, Austria, etc., played originally with a 78-card deck that includes four suits, four face-cards each, plus the tarot cards as trumps; from Old Italian tarocchi (plural); see tarot.
tarot (n.) Look up tarot at Dictionary.com
1590s, from French tarot (16c.), from Old Italian tarocchi (plural), of unknown origin, perhaps from Arabic taraha "he rejected, put aside." The deck first was used in Italy 14c., as playing cards as well as for fortune-telling. The tarots, strictly speaking, are the 22 figured cards added to the 56-card suits pack.
tarp (n.) Look up tarp at Dictionary.com
1906, American English, informal shortening of tarpaulin.
tarpaulin (n.) Look up tarpaulin at Dictionary.com
c. 1600, evidently a hybrid from tar (n.1) + palling, from pall "heavy cloth covering" (see pall (n.)); probably so called because the canvas sometimes is coated in tar to make it waterproof. Originally tarpawlin, tarpawling, etc., the spelling settled down early 18c.
Tarpeian rock (n.) Look up Tarpeian rock at Dictionary.com
rock face on the Capitoline Hill in Rome, from which persons convicted of treason were thrown headlong, from Latin (mons) Tarpeius "(rock) of Tarpeia," said to have been a Vestal virgin who betrayed the capitol to the Sabines and was buried at the foot of the rock. Her name probably is of Etruscan-Tyrrhenian origin.
tarpon (n.) Look up tarpon at Dictionary.com
large fish (Megalops atlanticus) of the herring family, 1680s, of uncertain origin, probably from a Native American word. Also formerly called jew-fish.
tarragon (n.) Look up tarragon at Dictionary.com
Artemisia Dracunculus, Eastern European plant of the wormwood genus, 1530s, from Medieval Latin tragonia, from Byzantine Greek tarchon, from Arabic tarkhon, from a non-Arabic source, perhaps Greek drakon "serpent, dragon" (via drakontion "dragonwort"); see dragon. From the same source come Spanish taragona, Italian targone, French estragon (with unetymological prefix). Its aromatic leaves long have been used for flavoring (especially vinegar).
tarry (v.) Look up tarry at Dictionary.com
early 14c., "to delay, retard" (transitive), of uncertain origin. Some suggest a connection to Latin tardare "to delay," or Old English tergan, tirgan "to vex, irritate, exasperate, provoke," which yielded a Middle English verb identical in form to this one. Intransitive meaning "to linger" is attested from late 14c. Related: Tarried; tarrying; tarrysome.
tarry (adj.) Look up tarry at Dictionary.com
1550s, from tar (n.1) + -y (2). Tarry-fingered "dishonest, thieving" is from 1825.
tarsal (adj.) Look up tarsal at Dictionary.com
"of or pertaining to the ankle or instep," 1817, from tarsus (n.1) + -al (1), or from medical Latin tarsalis.
tarsus (n.) Look up tarsus at Dictionary.com
the ankle bones collectively, 1670s, Modern Latin, from Greek tarsos "ankle, sole of the foot, rim of the eyelid," originally "flat surface, especially for drying," from PIE root *ters- "to dry" (cognates: Greek teresesthai "to be or become dry," tersainein "to make dry;" Latin terra "land, ground, soil," torrere "dry up, parch;" see terrain). The connecting notion is the bones of the "flat" of the foot (Greek tarsos podos).
tart (adj.) Look up tart at Dictionary.com
"having a sharp taste," 1520s, also attested once, obscurely, from late 14c., perhaps from Old English teart "painful, sharp, severe, rough" (in reference to punishment, pain, suffering), from Germanic *ter-t-, from PIE *der- (2) "to split, flay, peel" (see tear (v.1)), but the gap in the record is unexplained. Figurative use, with reference to words, speech, etc., is attested from c. 1600. Related: Tartly; tartness, both also absent in Middle English.
tart (n.1) Look up tart at Dictionary.com
"small pie," late 14c., from Old French tarte "flat, open-topped pastry" (13c.), possibly an alteration of torte, from Late Latin torta "round loaf of bread" (in Medieval Latin "a cake, tart"), perhaps from past participle of torquere "to twist."
tart (n.2) Look up tart at Dictionary.com
1887, "prostitute, immoral woman," from earlier use as a term of endearment to a girl or woman (1864), sometimes said to be a shortening of sweetheart. But another theory traces it to jam-tart (see tart (n.1)), which was British slang early 19c. for "attractive woman." Diminutive tartlet attested from 1890. To tart (something) up is from 1938. Related: Tarted.
tartan (n.) Look up tartan at Dictionary.com
"kind of woolen fabric," mid-15c., perhaps from Middle French tiretaine "strong, coarse fabric" (mid-13c.), from Old French tiret "kind of cloth," from tire "silk cloth," from Medieval Latin tyrius "cloth from Tyre" (see Tyrian).

If this is the source, spelling likely influenced in Middle English by tartaryn "rich silk cloth" (mid-14c.), from Old French tartarin "Tartar cloth," from Tartare "Tartar," the Central Asian people (see Tartar). Specific meaning "woolen or worsted cloth woven with crossing stripes of colors" is from c. 1500, formerly a part of the distinctive dress of Scottish Highlanders, each clan having its particular pattern.
tartar (n.) Look up tartar at Dictionary.com
"bitartrate of potash" (a deposit left during fermentation), late 14c., from Old French tartre, from Medieval Latin tartarum, from late Greek tartaron "tartar encrusting the sides of wine casks," perhaps of Semitic origin, but if so the exact source has not been identified. The purified substance is cream of tartar. Used generally in 17c. of encrustations from liquid contact; specific meaning "encrustation on teeth" (calcium phosphate) is first recorded 1806.
Tartar Look up Tartar at Dictionary.com
mid-14c. (implied in Tartary, "the land of the Tartars"), from Medieval Latin Tartarus, from Persian Tatar, first used 13c. in reference to the hordes of Ghengis Khan (1202-1227), said to be ultimately from Tata, a name of the Mongols for themselves. Form in European languages probably influenced by Latin Tartarus "hell" (e.g. letter of St. Louis of France, 1270: "In the present danger of the Tartars either we shall push them back into the Tartarus whence they are come, or they will bring us all into heaven").

The historical word for what now are called in ethnological works Tatars. A Turkic people, their native region was east of the Caspian Sea. Ghengis' horde was a mix of Tatars, Mongols, Turks, etc. Used figuratively for "savage, rough, irascible person" (1660s). To catch a Tartar "get hold of what cannot be controlled" is recorded from 1660s; original sense not preserved, but probably from some military story similar to the old battlefield joke:
Irish soldier (shouting from within the brush): I've captured one of the enemy.
Captain: Excellent! Bring him here.
Soldier: He won't come.
Captain: Well, then, you come here.
Soldier: I would, but he won't let me.
Among the adjectival forms that have been used are Tartarian (16c.), Tartarous (Ben Jonson), Tartarean (17c.); Byron's Tartarly (1821) is a nonce-word (but a good one). Tartar sauce is first recorded 1855, from French sauce tartare.
tartaric (adj.) Look up tartaric at Dictionary.com
1790, from tartar + -ic.
Tartarus (n.) Look up Tartarus at Dictionary.com
in Homer and older Greek mythology, the sunless abyss below Hades, from Greek Tartaros, of uncertain origin; "prob. a word of imitative origin, suggestive of something frightful" [Klein]. Later in Greek almost synonymous with Hades.
Tartuffe (n.) Look up Tartuffe at Dictionary.com
"pretender to piety," 1670s, from name of the principal character in the comedy by Molière (1664), apparently from Old French tartuffe "truffle" (see truffle), perhaps chosen for suggestion of concealment (Tartuffe is a religious hypocrite), or "in allusion to the fancy that truffles were a diseased product of the earth." Italian Tartufo is said to have been the name of a hypocritical character in Italian comedy.
Tarzan Look up Tarzan at Dictionary.com
name of character in a series of novels by U.S. fiction writer Edgar Rice Burroughs (1875-1950), introduced 1914.
Taser (n.) Look up Taser at Dictionary.com
1972, formed (probably on model of laser, etc.) from the initials of Tom Swift's electric rifle, a fictitious weapon. A word that threatens to escape the cage of its copyright, despite the strenuous efforts of the owners, who are within their rights to fight to hold it. They also insist, via their attorneys, that it be written all in capitals. Tom Swift was the hero of a series of early 20c. American sci-fi/adventure novels, one of which was titled "Tom Swift and His Electric Rifle." It seems to have spawned a verb, taze or tase. Related: Tased; tasing.
task (n.) Look up task at Dictionary.com
early 14c., "a quantity of labor imposed as a duty," from Old North French tasque (12c., Old French tasche, Modern French tâche) "duty, tax," from Vulgar Latin *tasca "a duty, assessment," metathesis of Medieval Latin taxa, a back-formation of Latin taxare "to evaluate, estimate, assess" (see tax (v.)). General sense of "any piece of work that has to be done" is first recorded 1590s. Phrase take one to task (1680s) preserves the sense that is closer to tax.

German tasche "pocket" is from the same Vulgar Latin source (via Old High German tasca), with presumable sense evolution from "amount of work imposed by some authority," to "payment for that work," to "wages," to "pocket into which money is put," to "any pocket."
task (v.) Look up task at Dictionary.com
1520s, "impose a task upon;" 1590s, "to burden, put a strain upon," from task (n.). Related: Tasked; tasking.