Chapter Trephine to Triatic of T by Webster's Dictionary (1913 Edition)

5. (Astron.) (a) A small constellation situated between Aries and Andromeda. (b) A small constellation near the South Pole, containing three bright stars.

Triangle spider (Zoöl.), a small American spider (Hyptiotes Americanus) of the family Ciniflonidæ, living among the dead branches of evergreen trees. It constructs a triangular web, or net, usually composed of four radii crossed by a double elastic fiber. The spider holds the thread at the apex of the web and stretches it tight, but lets go and springs the net when an insect comes in contact with it.

Triangled
(Tri"an`gled) a. Having three angles; triangular.

Triangular
(Tri*an"gu*lar) a. [L. triangularis: cf. F. triangulaire.]

1. Having three angles; having the form of a triangle.

2. (Bot.) Oblong or elongated, and having three lateral angles; as, a triangular seed, leaf, or stem.

Triangular compasses, compasses with three legs for taking off the angular points of a triangle, or any three points at the same time. — Triangular crab (Zoöl.), any maioid crab; — so called because the carapace is usually triangular. — Triangular numbers (Math.), the series of numbers formed by the successive sums of the terms of an arithmetical progression, of which the first term and the common difference are 1. See Figurate numbers, under Figurate.

Triangulares
(||Tri*an`gu*la"res) n. pl. [L.] (Zoöl.) The triangular, or maioid, crabs. See Illust. under Maioid, and Illust. of Spider crab, under Spider.

Triangularity
(Tri*an`gu*lar"i*ty) n. The quality or state of being triangular. Bolingbroke.

Triangularly
(Tri*an"gu*lar*ly) adv. In a triangular manner; in the form of a triangle. Dampier.

Triangulate
(Tri*an"gu*late) v. t. [imp. & p. p. Triangulated ; p. pr. & vb. n. Triangulating.]

1. To divide into triangles; specifically, to survey by means of a series of triangles properly laid down and measured.

2. To make triangular, or three-cornered.

Triangulation
(Tri*an`gu*la"tion) n. [Cf. F. triangulation.] (Surv.) The series or network of triangles into which the face of a country, or any portion of it, is divided in a trigonometrical survey; the operation of measuring the elements necessary to determine the triangles into which the country to be surveyed is supposed to be divided, and thus to fix the positions and distances of the several points connected by them.

Triarchy
(Tri"ar*chy) n.; pl. Triarchies [Gr. (see Tri-) + to rule.] Government by three persons; a triumvirate; also, a country under three rulers. Holland.

Triarian
(Tri*a"ri*an) a. [L. triarii, pl., a class of Roman soldiers who formed the third rank from the front, fr. tres, tria, three.] Occupying the third post or rank. [Obs.] Cowley.

Triarticulate
(Tri`ar*tic"u*late) a. [Pref. tri- + articulate.] (Zoöl.) Having three joints.

Trias
(Tri"as) n. [L., triad. See Triad.] (Geol.) The formation situated between the Permian and Lias, and so named by the Germans, because consisting of three series of strata, which are called in German the Bunter sandstein, Muschelkalk, and Keuper.

Triassic
(Tri*as"sic) a. (Geol.) Of the age of, or pertaining to, the Trias. — n. The Triassic formation.