Words related to tri-

three (adj., n.)

"1 more than two; the number which is one more than two; a symbol representing this number;" Old English þreo, fem. and neuter (masc. þri, þrie), from Proto-Germanic *thrijiz (source also of Old Saxon thria, Old Frisian thre, Middle Dutch and Dutch drie, Old High German dri, German drei, Old Norse þrir, Danish tre), from nominative plural of PIE root *trei- "three" (source also of Sanskrit trayas, Avestan thri, Greek treis, Latin tres, Lithuanian trys, Old Church Slavonic trye, Irish and Welsh tri "three").

3-D first attested 1952, abbreviation of three-dimensional (1878). Three-piece suit is recorded from 1909. Three cheers for ______ is recorded from 1751. Three-martini lunch is attested from 1972. Three-ring circus is recorded by 1898. Three-sixty "complete turnaround" is from 1927, originally among aviators, in reference to the number of degrees in a full circle. Three musketeers translates French les trois mousquetaires, title of the 1844 novel by Alexandre Dumas père.

drill (n.3)

also drilling, kind of coarse, stout twilled cloth, 1743, from French drill, from German drillich "heavy, coarse cotton or linen fabric," from Old High German adjective drilich "threefold," from Latin trilix (genitive trilicis) "having three threads, triple-twilled," from tri- (see tri-) + licium "thread," a word of unknown etymology. So called in reference to the method of weaving it.

trammel (n.)
mid-14c., "net to catch fish" (implied in trammeller "one who fishes with a trammel net"), from Old French tramail "fine-gauged fishnet" (13c.), from Late Latin tremaculum, perhaps meaning "a net made from three layers of meshes," from Latin tri- "three" (see tri-) + macula "a mesh" (see mail (n.2)). Meaning "anything that hinders" is from 1650s, originally "a hobble for a horse" (c. 1500). Italian tramaglio, Spanish trasmallo are French loan-words.
trefoil (n.)
late 14c., type of clover, from Anglo-French trifoil (13c.), Old French trefueil "clover, clover-leaf," from Latin trifolium "three-leaved plant," from tri- "three" (see tri-) + folium "leaf" (from PIE root *bhel- (3) "to thrive, bloom"). As a type of ornamental figure in medieval architecture, early 15c.
trellis (n.)

late 14c., "lattice, grating," from Old French trelis, trellis "trellis, fence," originally "sackcloth," from Vulgar Latin *trilicius, from Latin trilicis, genitive of trilix "having three threads, triple-twilled," from tri- (see tri-) + licium "thread," a word of unknown etymology.

Sense extended in Old French to things "woven" of iron, etc., which brought on influence of Old French treille "vine trellis," perhaps from Latin trichila "bower, arbor," which is apparently from Latin triclinium "couch extending round three sides of a table" (for reclining on at meals; from PIE root *klei- "to lean"). Meaning "lattice used to support growing vines" is from 1510s. As a verb, c. 1400. Related: Trellised.

triangle (n.)
late 14c., from Old French triangle (13c.), from Latin triangulum "triangle," noun use of neuter of adjective triangulus "three-cornered, having three angles," from tri- "three" (see tri-) + angulus "corner, angle" (see angle (n.)).
triannual (adj.)
1630s, from tri- + annual (adj.). Related: Triannually.
triathlon (n.)
1970, from tri- "three" + Greek athlon "contest;" formed on model of decathlon, biathlon, etc. Originally of various combinations of events; one of the earliest so called combined clay-pigeon shooting, fly-fishing, and horse-jumping; another was cross-country skiing, target shooting, and a giant slalom run; and a third connected to the U.S. Army involved shooting, swimming, and running. Applied to the combination of a long swim, a bicycle-race, and a marathon by 1981.
tricentennial (adj.)

also tri-centennial, "comprising three hundred years; including or relating to an interval of three hundred years," 1818; as a noun, "day observed as a festival in commemoration of something that happened three hundred years before," 1872. See tri- + centennial.