Online Etymology Dictionary

tenterhooks (n.): late 15c., "one of the hooks that holds cloth on a tenter," from tenter + hook (n.). The figurative phrase on tenterhooks "in painful suspense" is from 1748; earlier to be on tenters (1530s).
tenth: mid-12c., tenðe; see ten + -th. Replacing Old English teoða (West Saxon), teiða (Northumbrian).
tenuious: late 15c., from Latin tenuis "thin" (see tenuous) + -ous.
tenuous (adj.): 1590s, irregularly formed from Latin tenuis "thin," from PIE root *ten- "to stretch" (cf. Sanskrit tanuh "thin," literally "stretched out;" see tenet) + -ous. The correct form with respect to the Latin is tenuious. The sense of "having slight importance, not substantial" is found from c.1817.
tenure (n.): early 15c., "holding of a tenement," from Anglo-French and Old French tenure "a tenure, estate in land" (13c.), from Old French tenir "to hold," from Vulgar Latin *tenire, from Latin tenere "to hold" (see tenet). The sense of "condition or fact of holding a status, position, or occupation" is first attested 1590s. Meaning "guaranteed tenure of office" (usually at a university or school) is recorded from 1957.
teocalli (n.): 1570s, from American Spanish, from Nahuatl (Aztec) teohcalli, literally "temple, church," from teotl "god" + calli "house."
teonanacatl (n.): native name for a hallucinogenic fungi (Psilocybe mexicana) found in Central America, 1875, from Nahuatl, from teotl "god" + nancatl "mushroom."
tepee (n.): 1743, ti pee, from Dakota (Siouan) thipi "dwelling, house."
tephromancy (n.): 1650s, "divination by means of ashes," from Greek tephra "ashes" + manteia "divination," from mantis "prophet" (see mania).
tepid (adj.): c.1400, from Latin tepidus "lukewarm," from tepere "be warm," from PIE root *tep- "warm" (cf. Sanskrit tapati "makes warm, heats, burns," tapah "heat;" Avestan tafnush "fever;" Old Church Slavonic topiti "to warm," teplu "warm;" Old Irish tene "fire;" Welsh tes "heat").
tequila (n.): 1849, from American Spanish tequila, from Tequila, name of a district in central Mexico noted for the fine quality of its tequila. Tequila sunrise is attested by 1965.
ter-: word-forming element meaning "thrice, three times," from Latin ter "thrice," from *tris-, from root of three. Cf. Latin tertius "third."
tera-: prefix used in forming large units of measure (e.g. terabyte), 1947, from Greek teras (genitive teratos) "marvel, monster."
terabyte (n.): by 1982, from tera- + byte.
teratogen (n.): 1959, from comb. form of Greek teras (genitive teratos) "marvel, monster" + -gen.
teratogenic (adj.): "causing the formation of monsters," 1879, from teratogeny (1857), from comb. form of Greek teras (genitive teratos) "marvel, monster" + -genic.
teratology (n.): "study of marvels and monsters," 1670s, from comb. form of Greek teras (genitive teratos) "marvel, monster" + -logy.
tercel (n.): "male falcon," late 14c., from Old French tercel (c.1200), from Medieval Latin tertiolus, from Latin tertius "third, a third," from root of tres "three" (see three). Various theories as to why it is called this; one says it's because the males are a third smaller than the females, another because a third egg in the nest (smaller than the other two) is believed always to produce a male bird.
tercentenary (n.): 1844, "pertaining to a period of 300 years," from ter- "three times" + centenary.
terceroon (n.): offspring of a white and a mulatto, 1760, from Spanish *terceron, from tercero "a third (person)," from tercio "third," from Latin tertius "a third," from root of tres "three" (see three). So called from being third in descent from a Negro.
tercet (n.): "three successive lines rhyming together," 1590s, from Italian terzetto, diminutive of terzo "third," from Latin tertius (see third). Spelling influenced by French tercet, from the Italian.
terebinth (n.): Mediterranean tree, a member of the sumac family, late 14c., from Old French therebint (13c.), from Latin terebinthus (Pliny), from Greek terebinthos, probably of foreign origin (Creto-Minoic?). The tree is the source of Chian turpentine.
tergiversate (v.): 1650s, from Latin tergiversatus, past participle of tergiversari "be evasive," literally "to turn one's back" (see tergiversation). Related: Tergiversated; tergiversating.
tergiversation (n.): turning dishonestly from a straightforward action or statement; shifting, shuffling, equivocation, 1570, from Latin tergiversationem (nominative tergiversatio) "a shifting, evasion," from past participle stem of tergiversari "turn one's back on, evade," from tergum "the back" (of unknown origin) + versare "to spin, turn" (see versus).
teriyaki: 1962, from Japanese, from teri "gloss, lustre" + yaki "roast."
term (n.): early 13c., terme "limit in time, set or appointed period," from Old French terme "limit of time or place" (11c.), from Latin terminus "end, boundary line," related to termen "boundary, end" (see terminus). Old English had termen "term, end," from Latin. Sense of "period of time during which something happens" first recorded c.1300, especially of a school or law court session (mid-15c.).

The meaning "word or phrase used in a limited or precise sense" is first recorded late 14c., from Medieval Latin use to render Greek horos "boundary," employed in mathematics and logic. Meaning "completion of the period of pregnancy" is from 1844. Term-paper in U.S. educational sense is recorded from 1931.
term (v.): "to give a particular name to," mid-16c., from term (n.). Related: Termed; terming.
termagant (n.): c.1500, "violent, overbearing person" (especially of women), from Teruagant, Teruagaunt (c.1200), name of a fictitious Muslim deity appearing in medieval morality plays, from Old French Tervagant, a proper name in "Chanson de Roland" (c.1100), of uncertain origin.
terminal (adj.): mid-15c., "relating to or marking boundaries," from Latin terminalis "pertaining to a boundary or end, final," from terminus "end, boundary line" (see terminus). Meaning "fatal" (terminal illness) is first recorded 1891. Sense of "situated at the extreme end of something" is from 1805. Slang meaning "extreme" first recorded 1983.
terminal (n.): "end point of a railway line," 1888, from terminal (adj.); sense of "device for communicating with a computer" is first recorded 1954.
terminate (v.): 1610s, "to bring to an end," from Latin terminatus, past participle of terminare "to limit, end" (see terminus). Sense of "to come to an end" is recorded from 1640s; meaning "dismiss from a job" is recorded from 1973; that of "to assassinate" is from 1975. Related: Terminated; terminating.
termination (n.): late 14c., "authoritative resolution of a matter," from Old French terminacion and directly from Latin terminationem (nominative terminatio) "a fixing of boundaries, bounding, determining," from past participle stem of terminare "to limit, end" (see terminus). Meaning "end of a person's employment" is recorded from 1961; meaning "artificial end of a pregnancy" is attested from 1969; sense of "assasination" is recorded from 1975.
terminator (n.): 1770, "line of separation between the bright and dark parts of a moon or planet," from Latin terminator, from terminare (see terminus). Meaning "one who terminates (something)" is attested from 1846.
terminer (n.): "a determining," legal term, from French terminer "to end," from Latin terminare (see terminus; cf. also oyer).
terminology (n.): 1801, from German Terminologie (1786), a hybrid coined by C.G. Schütz of Jena, from Medieval Latin terminus "word, expression" (see terminus) + Greek -logia "a dealing with, a speaking of" (see -logy).
terminus (n.): 1550s, "goal, end, final point," from Latin terminus (plural termini) "end, boundary line," from PIE root *ter-, base of words meaning "peg, post, boundary, marker goal" (cf. Sanskrit tarati "passes over, crosses over," Hittite tarmaizzi "he limits," Greek terma "boundary, end, limit"). In ancient Rome, Terminus was the name of the deity who presided over boundaries and landmarks, focus of the important Roman festival of Terminalia (held Feb. 23, the end of the old Roman year). Meaning "either end of a transportation line" is first recorded 1836.
termite (n.): 1849, back-formation from plural form termites (1781), from Modern Latin termites (three syllables), plural of termes (genitive termitis), a special use of Late Latin termes "woodworm, white ant," altered (by influence of Latin terere "to rub, wear, erode") from earlier Latin tarmes. Their nest is a terminarium (1863).
terms (n.): "limiting conditions," early 14c.; see term. Hence expressions such as come to terms, make terms, on any terms, etc. Meaning "standing, footing, mutual relations," as in expression on good terms (with someone), is recorded from 1540s.
tern (n.): gull-like shore bird (subfamily Sterninae), 1670s, via East Anglian dialect, from a Scandinavian source (cf. Danish terne, Swedish tärna, Færoese terna) related to Old Norse þerna "tern," cognate with Old English stearn "starling."
ternary (adj.): early 15c., from Late Latin ternarius "consisting of three," from terni "three by three," from ter "thrice," which is related to tres "three" (see three).
Terpsichore: the muse of the dance, Greek Terpsikhore, literally "enjoyment of dance," from terpein "to delight" (from PIE root *terp- "to satisfy;" cf. Sanskrit trpyati "takes one's fill," Lithuanian tarpstu "to thrive, prosper") + khoros "dance, chorus" (see chorus).
terpsichorean (adj.): "pertaining to dancing," 1869, literally "of Terpsichore," from Latinized form of Greek Terpsikhore, muse of dancing and dramatic chorus (see Terpsichore). Hence theatrical slang terp "stage dancer, chorus girl" (1937).
terr: Rhodesian slang abbreviation of terrorist, 1976, used in reference to guerrilla fighting against white minority government.
terra (n.): Latin, literally "earth" (see terrain).
terra firma (n.): c.1600, "part of the Italian mainland ruled by Venice," from Modern Latin terra firma, literally "firm land," from Latin terra "earth, land" (see terrain) + firma "firm," fem. of firmus (see firm (adj.)). Meaning "the land" (as distinct from "the sea") is first attested 1690s.
terra incognita (n.): "unknown or unexplored region," 1610s, Latin, literally "unknown land," from terra (see terrain) + fem. of incognito.
terra-cotta (n.): 1722, from Italian terra cotta, literally "cooked earth," from terra "earth" (see terrain) + cotta "baked," from Latin cocta, fem. past participle of coquere (see cook (n.)). As a color name for brownish-red, attested from 1882.
terrace (n.): 1510s, "gallery, portico, balcony," later "flat, raised place for walking" (1570s), from Middle French terrace, from Old French terrasse "platform (built on or supported by a mound of earth)," from Vulgar Latin *terracea, fem. of *terraceus "earthen, earthy," from Latin terra "earth, land" (see terrain). As a natural formation in geology, attested from 1670s.
terrain (n.): 1727, "ground for training horses," from French terrain "piece of earth, ground, land," from Old French (12c.), from Vulgar Latin *terranum, from Latin terrenum "land, ground," from neuter of terrenus "of earth, earthly," from terra "earth, land," literally "dry land" (as opposed to "sea"); from PIE root *ters- "to dry" (cf. Sanskrit tarsayati "dries up," Avestan tarshu- "dry, solid," Greek teresesthai "to become or be dry," Latin torrere "dry up, parch," Gothic þaursus "dry, barren," Old High German thurri, German dürr, Old English þyrre "dry;" Old English þurstig "thirsty"). Meaning "tract of country, considered with regard to its natural features" first attested 1766.
terran (adj.): "of or pertaining to the planet Earth," 1881, in science fiction writing, from Latin terra (see terrain). Also used as a noun meaning "inhabitant of the Earth" (1953). An earlier form, terrene was used in Middle English in sense of "belonging to this world, earthly, secular, temporal" (c.1300), later, "of the Earth as a planet" (1630s).