Online Etymology Dictionary

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 (e.g. Abenaki turepe, Delaware tulpe "turtle"). Subsequently extended to allied species in South America, East Indies, China, North Africa.
terrarium (n.): 1890, from Modern Latin, formed from Latin terra "land" (see terrain) + -arium, abstracted from aquarium.
terrazzo (n.): type of flooring material, 1902, from Italian terrazzo "terrace, balcony" (see terrace).
terrene (adj.): 14c., ultimately from Latin terrenus, from terra "earth" (see terrain).
terrestrial (adj.): early 15c., from Latin terrestris "earthly," 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.): early 15c., "causing terror, frightful," from Old French terrible (12c.), from Latin terribilis "frightful," from terrere "fill with fear," from PIE root *tres- "to tremble" (cf. Sanskrit trasati "trembles," Avestan tarshta "feared, revered," Greek treëin "to tremble," Lithuanian triseti "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," 1520s, see 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.): mid-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," from terrere "fill with fear" (see terrible) + root of facere "to make" (see factitious). Weakened sensed of "very great, severe" (e.g. terrific headache) appeared 1809; colloquial sense of "excellent" began 1888.
terrify (v.): 1570s, from Latin terrificare "to frighten," from terrificus "causing terror" (see terrific). Related: Terrified; terrifying.
terrine (n.): 1706, obsolete original form of tureen.
territorial (adj.): 1768, from Late Latin territorialis, from territorium (see territory). In reference to British regiments, from 1881. Territorial army "British home defense" is from 1908. Territorial waters is from 1841; territorial imperative "animal need to claim and defend territory" is from 1966.
territoriality (n.): 1839, as a concept in international law, from territorial + -ity.
territory (n.): early 15c., "land under the jurisdiction of a town, state, etc.," probably from Latin territorium "land around a town, domain, district," from terra "earth, land" (see terrain) + -orium, suffix denoting place (see -ory).

An alternative theory, somewhat supported by the vowels of the original Latin word, suggests derivation from terrere "to frighten" (see terrible); thus territorium would mean "a place from which people are warned off." Sense of "any tract of land, district, region" is first attested c.1600. Specific U.S. sense of "organized self-governing region not yet a state" is from 1799.
terror (n.): late 14c., "great fear," from Old French terreur (14c.), from Latin terrorem (nominative terror) "great fear, dread," from terrere "fill with fear, frighten," from PIE root *tre- "shake" (see terrible). Meaning "quality of causing dread" is attested from 1520s; terror bombing first recorded 1941, with reference to German air attack on Rotterdam. Sense of "a person fancied as a source of terror" (often with deliberate exaggeration, as of a naughty child) is recorded from 1883. The Reign of Terror in French history (March 1793-July 1794) so called in English from 1801. Old English words for "terror" included broga and egesa.
terrorism (n.): 1795, in specific sense of "government intimidation during the Reign of Terror in France" (March 1793-July 1794), from French terrorisme (1798), from Latin terror (see terror).
If the basis of a popular government in peacetime is virtue, its basis in a time of revolution is virtue and terror -- virtue, without which terror would be barbaric; and terror, without which virtue would be impotent. [Robespierre, speech in French National Convention, 1794]
General sense of "systematic use of terror as a policy" is first recorded in English 1798. At one time, a word for a certain kind of mass-destruction terrorism was dynamitism (1883); and during World War I frightfulness (translating German Schrecklichkeit) was used in Britain for "deliberate policy of terrorizing enemy non-combatants."
terrorist (n.): in the modern sense, 1944, especially in reference to Jewish tactics against the British in Palestine -- earlier it was used of extremist revolutionaries in Russia (1866); and Jacobins during the French Revolution (1795) -- from French terroriste; see terror + -ist (also cf. terrorism). The tendency of one party's terrorist to be another's guerilla or freedom fighter was noted in reference to the British action in Cyprus (1956) and the war in Rhodesia (1973). The word terrorist has been applied, at least retroactively, to the Maquis resistance in occupied France in World War II (e.g. in the "Spectator," Oct. 20, 1979).
terrorize (v.): "coerce or deter by terror," 1823, from terror + -ize (also cf. terrorism). Related: Terrorized; terrorizing.
terry (n.): "loop raised in pile-weaving, left uncut," 1784, possibly an alteration of French tiré "drawn," from past participle of tirer "draw out" (cf. cognate German gezogener Sammet "drawn velvet").
terse (adj.): 1590s (implied in tersely), "clean-cut, burnished, neat," from French ters "clean," from Latin tersus "wiped off, clean, neat," from past participle of tergere "to rub, polish, wipe." Sense of "concise or pithy in style or language" is from 1777, which led to a general sense of "neatly concise." The pejorative meaning "brusque" is a fairly recent development.
tertiary (adj.): 1650s, "of the third order, rank, degree, etc.," from Latin tertiarius "of or pertaining to a third," from tertius "third, a third," from root of tres "three" (see three). The geological sense (with capital T-) of "era after the Mesozoic" (which formerly was called the Secondary) is attested from 1794, after Italian terziari, used in this sense 1760 by Italian geologist Giovanni Arduino (1714-1795).
tertium quid (n.): 1724, Latin, literally "third something," loan-translation of Greek triton ti (Plato), used in alchemy for "unidentified element present in a combination of two known ones."
terza rima (n.): 1819, Italian, literally "third rhyme." Dante's measure: a-b-a-b-c-b-c-d-c-, etc.
tesla (n.): 1960, "unit of magnetic flux density," from Nikola Tesla (1856-1943), Croatian-born U.S. engineer. Tesla coil is attested from 1896.
tessellated (adj.): 1690s, from Late Latin tessellatus "made of small square stones or tiles," from tessella "small square stone or tile," diminutive of tessera "a cube or square of stone or wood," perhaps from Greek tessera, neuter of tesseres, Ionic variant of tessares "four" (see four), in reference to four corners. Related: Tessellate (1826, adj.; 1791, v.; 1909, n.); tessellating.
tessellation (n.): 1650s, from Late Latin tessellatus (see tessellated).
tessera (n.): plural tesserae, 1650s, from Latin tessera, from Ionic Greek tesseres (Attic tessares) "four" (see four).
tesseract (n.): 1888, from tessera + Greek aktis "ray" (see actino-).
test (n.): late 14c., "small vessel used in assaying precious metals," from Old French test, from Latin testum "earthen pot," related to testa "piece of burned clay, earthen pot, shell" (cf. Latin testudo "tortoise") and texere "to weave" (cf. Lithuanian tistas "vessel made of willow twigs;" see texture (n.)).

Sense of "trial or examination to determine the correctness of something" is recorded from 1590s. The connecting notion is "ascertaining the quality of a metal by melting it in a pot." Test Act was the name given to various laws in English history meant to exclude Catholics and Nonconformists from office, especially that of 1673, repealed 1828. Test drive (v.) is first recorded 1954.
test (v.): 1748, "to examine the correctness of," from test (n.). Related: Tested; testing.
test-tube (n.): 1809, from test (n.) + tube (n.). So called because it originally was used to test the properties of liquids. Test-tube baby is recorded from 1935.
testament (n.): late 13c., "last will disposing of property," from Latin testamentum "a will, publication of a will," from testari "make a will, be witness to," from testis "witness," from PIE *tris- "three," on the notion of "third person, disinterested witness."

Use in reference to the two divisions of the Bible (c.1300) is from Late Latin vetus testamentum and novum testamentum, loan-translations of Greek palaia diatheke and kaine diatheke. Late Latin testamentum in this case was a mistranslation of Greek diatheke, which meant both "covenant, dispensation" and "will, testament," and was used in the former sense in the account of the Last Supper (see testimony) but subsequently was interpreted as Christ's "last will."
testamentary (adj.): mid-15c., from Latin testamentarius, from testamentum (see testament).
testate (adj.): "having left a valid will," late 15c., from Latin testatus, past participle of testari "make a will, be witness to, declare" (see testament).
testator (n.): mid-15c., from Anglo-French testatour (c.1300), from Late Latin testatorem, from testari (see testate).
tester (n.1): "one who tests," 1660s, agent noun from test (v.).
tester (n.2): "canopy over a bed," late 14c., from Medieval Latin testerium, from testera "head stall," from Late Latin testa (capitis) "skull," from Latin, literally "earthenware, pot." The "head" sense (originally merely humorous) is the source of tester in obsolete senses of "piece of armor for the head" (late 14c.) and "coin of Henry VIII" (1546), the first English coin to bear a true portrait. For sense development, cf. Old English cuppe "cup" from source of German kopf "head."
testicle (n.): 1590s, alteration of testicule (early 15c.), from Latin testiculus, diminutive of testis "testicle" (see testis). The Old English was herþan, probably originally "leather bag" (cf. heorþa "deer-skin"). The commonest slang terms for them in other languages are words that mean "balls," "stones," "nuts," "eggs."
testify (v.): late 14c., "to serve as evidence of," from Latin testificari "bear witness," from testis "witness" (see testament) + root of facere "to make" (see factitious). Biblical sense of "openly profess one's faith and devotion" is attested from 1520s. Related: Testified; testifying.
testimonial (adj.): early 15c., "of or pertaining to testimony," in letters testimonial from Middle French lettres testimoniaulx, from Latin litteræ testimoniales, from testimonium (see testimony). The noun meaning "writing testifying to one's qualification or character" is recorded from 1570s; that of "gift presented as an expression of appreciation" is from 1838.
testimony (n.): late 14c., "the Ten Commandments," from Late Latin testimonium (Vulgate), along with Greek to martyrion (Septuagint), translations of Hebrew 'eduth "attestation, testimony" (of the Decalogue), from 'ed "witness." Meaning "evidence, statement of a witness" first recorded early 15c., from Old French testimonie (11c.), from Latin testimonium "evidence, proof, testimony," from testis "witness" (see testament) + -monium, suffix signifying action, state, condition.
testis (n.): (plural testes), 1704, from Latin testis "testicle," usually regarded as a special application of testis "witness" (see testament), presumably because it "bears witness" to virility (cf. Greek parastates, literally "one that stands by;" and French slang témoins, literally "witnesses"). But Buck thinks Greek parastatai "testicles" has been wrongly associated with the legal sense of parastates "supporter, defender" and suggests instead parastatai in the sense of twin "supporting pillars, props of a mast," etc. Walde, meanwhile, suggests a connection between testis and testa "pot, shell, etc."
testosterone (n.): male sex hormone, 1935, from German Testosteron (1935), coined from a presumed comb. form of Latin testis "testicle" (see testis) + ster(ol) (see steroid) + chemical ending -one.
testy (adj.): c.1500, "impetuous, rash," from Middle English testif "headstrong" (late 14c.), from Anglo-French testif, Old French testu "stubborn," literally "heady," from teste "head," from Late Latin testa "skull," in classical Latin "pot, shell" (see tester (n.2)). Meaning "easily irritated" is first recorded 1520s.
Tet: Vietnamese lunar new year, 1885. The North Vietnamese Tet Offensive in the U.S. Vietnam War began Jan. 30, 1968.
tetanus (n.): late 14c., from Latin tetanus, from Greek tetanos "muscular spasm," literally "a stretching, tension," from teinein "to stretch" (see tenet); so called because the disease is characterized by violent spasms and stiffness of muscles.
tetany (n.): 1890, from French tétanie "intermitent tetanus," from Modern Latin tetania (see tetanus).
tetched (adj.): 1930, U.S. colloquial variant of touched in the sense of "slightly crazy" (see touch).
tetchy (adj.): "easily irritated," 1592, teachie, in "Romeo & Juliet" I.iii.32; of uncertain origin. Perhaps from Middle English tatch "a mark, quality," derived via Old French from Vulgar Latin *tecca, from a Germanic source akin to Old English tacen (see token).