teratogeny (n.)
"the production of monsters," 1855, from terato- + -geny. Related: Teratogenesis.
teratology (n.)
"study of marvels and monstrosities," 1842, from terato- + -logy. Earlier it meant "marvelous narrative" (1670s), from Greek teratologia "a telling of marvels." Related: Teratological; teratologist.
teratoscopy (n.)
"augury from prodigies," 1660s; see terato- + -scopy.
terbium (n.)
1843, from Latinized form of Ytterby, Swedish town near the place where mineral containing the element was found (see Ytterbium) + -ium.
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 (adj.)
1832, "pertaining to a period of 300 years," from ter- "three times" + centenary. As a noun from 1835. Related: Tercentennial (1862 as an adjective; 1872 as a noun).
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, earlier terminthos, probably from a non-Indo-European language (Klein suggests Creto-Minoic). The tree is the source of Chian turpentine. Related: Terebinthine; terebinthaceous.
tergiversate (v.)
1650s, back-formation from tergiversation, or else from Latin tergiversatus, past participle of tergiversari "be evasive," literally "to turn one's back." Related: Tergiversated; tergiversating.
tergiversation (n.)
turning dishonestly from a straightforward action or statement; shifting, shuffling, equivocation, 1560s, from Latin tergiversationem (nominative tergiversatio) "a shifting, evasion, declining, refusing," 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).
1962, from Japanese, from teri "gloss, luster" + yaki "roast."
term (n.)
c.1200, terme "limit in time, set or appointed period," from Old French terme "limit of time or place, date, appointed time, duration" (11c.), from Latin terminus "end, boundary line," in Medieval Latin "expression, definition," 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 of terminus to render Greek horos "boundary," employed in mathematics and logic. Hence in terms of "in the language or phraseology peculiar to." 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," 1550s, 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. As an adjective from 1590s.
terminable (adj.)
early 15c., from Latin stem of terminate (v.) + -able.
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. Related: Termninally.
terminal (n.)
"end point of a railway line," 1888, from terminal (adj.); sense of "device for communicating with a computer" is first recorded 1954. Earlier "final part of a word" (1831).
terminate (v.)
early 15c., "bring to an end," from Latin terminatus, past participle of terminare "to limit, set bounds, end" (see terminus). Intransitive 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 (13c.) and directly from Latin terminationem (nominative terminatio) "a fixing of boundaries, a bounding, determining," noun of action 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 Late Latin terminator "he who sets bounds," agent noun from terminare (see terminus). Meaning "one who terminates" (something) is attested from 1846.
terminer (n.)
"a determining," legal term, from French terminer "to end," in Old French "to decide, rule on," from Latin terminare (see terminus; also see oyer).
terminology (n.)
1770, from German Terminologie, a hybrid coined by Christian Gottfried Schütz (1747-1832), professor of poetry and rhetoric at Jena, from Medieval Latin terminus "word, expression" (see terminus) + Greek -logia "a dealing with, a speaking of" (see -logy). Related: Terminological.
terminus (n.)
1550s, "goal, end, final point," from Latin terminus (plural termini) "end, boundary line," from PIE *ter-men-, from root *ter-, base of words meaning "peg, post, boundary, marker, goal" (cognates: Sanskrit tarati "passes over, crosses over," tarantah "sea;" Hittite tarmaizzi "he limits;" Greek terma "boundary, end, limit;" Gothic þairh, Old English þurh "through;" Old English þyrel "hole;" Old Norse þrömr "edge, chip, splinter").

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). Earlier in English known as wood ant or white ant.
terms (n.)
"limiting conditions," early 14c.; see term (n.). 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 (compare Danish terne, Swedish tärna, Færoese terna) related to Old Norse þerna "tern" (also "maid-servant"), cognate with Old English stearn.
ternary (adj.)
"threefold," 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 (n.)
the muse of the dance, Greek Terpsikhore, literally "enjoyment of dance," from terpein "to delight" (from PIE root *terp- "to satisfy;" cognates: 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 (n.)
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 (Modern French terasse), from Old French terrasse (12c.) "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. In street names, originally in reference to a row of houses along the top of a slope, but lately applied arbitrarily as a fancy name for an ordinary road. As a verb from 1610s, "to form into a terrace." Related: Terraced.
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," noun use of neuter of terrenus "of earth, earthly," from terra "earth, land," literally "dry land" (as opposed to "sea"); from PIE root *ters- "to dry" (cognates: 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).
terrapin (n.)
North American turtle, 1670s, earlier torope (1610s), from an Algonquian source (such as Abenaki turepe, Munsee (Delaware) tolpew "turtle"). Subsequently extended to allied species in South America, East Indies, China, North Africa.
terraqueous (adj.)
"consisting of both land and water," 1650s, from comb. form of Latin terra "earth" (see terrain) + aqueous.
terrarium (n.)
1877, from Modern Latin, formed from Latin terra "land" (see terrain) + -arium, abstracted from aquarium.
terrazzo (n.)
type of flooring material, 1893, from Italian terrazzo "terrace, balcony" (see terrace).
terrene (adj.)
"earthly, terrestrial, of or pertaining to the earth," c.1300, from Anglo-French terreine, Old French terrien, from Latin terrenus "on the earth, earthly," from terra "earth" (see terrain).
terrestrial (adj.)
late 14c., "of or pertaining to the earth," with + -al (1) + from Latin terrestris "earthly, of the earth, on land," from terra "earth" (see terrain). Originally opposed to celestial; natural history sense of "living on land" is attested from 1630s. The noun meaning "a human being, a mortal" is recorded from 1590s.
terrible (adj.)
late 14c., "causing terror, awe, or dread; frightful," from Old French terrible (12c.), from Latin terribilis "frightful," from terrere "fill with fear," from PIE root *tres- "to tremble" (cognates: Sanskrit trasati "trembles," Avestan tarshta "feared, revered," Greek treëin "to tremble," Lithuanian trišeti "to tremble," Old Church Slavonic treso "I shake," Middle Irish tarrach "timid"). Weakened sense of "very bad, awful" is first attested 1590s.
terribly (adv.)
"dreadfully, so as to cause terror, in a horrible manner," mid-15c., from terrible + -ly (2). In the sense of "extremely" it is first recorded 1833; in the sense of "extremely badly" it dates from 1930.
terrier (n.)
kind of dog, early 15c., from Old French chien terrier "terrier dog," literally "earth dog," from Medieval Latin terrarius "of earth," from Latin terra "earth" (see terrain). So called because the dogs pursue their quarry (foxes, badgers, etc.) into their burrows.
terrific (adj.)
1660s, "frightening," from Latin terrificus "causing terror or fear, frightful," from terrere "fill with fear" (see terrible) + root of facere "to make" (see factitious). Weakened sensed of "very great, severe" (as in terrific headache) appeared 1809; inverted colloquial sense of "excellent" began 1888. Related: Terrifically.
terrify (v.)
1570s, from Latin terrificare "to frighten, make afraid," from terrificus "causing terror" (see terrific). Related: Terrified; terrifying.
terrine (n.)
earthenware dish, 1706, obsolete original form of tureen.