‖n. [ NL. See Trigon. So called in allusion to the triangular shape of some species. ] (Zool.) A genus of pearly bivalve shells, numerous extinct species of which are characteristic of the Mesozoic rocks. A few living species exist on the coast of Australia. [ 1913 Webster ]

n. [ L. trigonum, Gr. &unr_;; &unr_; (see Tri-) + &unr_; a corner, angle: cf. F. trigone. ] [ 1913 Webster ]

1. A figure having three angles; a triangle. [ 1913 Webster ]

2. (Astrol.) (a) A division consisting of three signs. (b) Trine, an aspect of two planets distant 120 degrees from each other. Hutton. [ 1913 Webster ]

3. (Gr. & Rom. Antiq.) (a) A kind of triangular lyre or harp. (b) A kind of game at ball played by three persons standing at the angular points of a triangle. [ 1913 Webster ]

a. Having three angles, or corners; triangular; as, a trigonal stem, one having tree prominent longitudinal angles. [ 1913 Webster ]

[ 1913 Webster ]

‖n. [ F., literally, a trigon. ] (Anat.) A smooth triangular area on the inner surface of the bladder, limited by the apertures of the ureters and urethra. [ 1913 Webster ]

4. (Zool.) The cutting region of the crown of an upper molar, usually the anterior part. That of a lower molar is the [ Webster 1913 Suppl. ]

a. [ Gr. &unr_; triangle + &unr_; horn. ] (Zool.) Having horns with three angles, like those of some species of goats. [ 1913 Webster ]

a. [ See Trigon; Odonto. ] See Trituberculy. [ Webster 1913 Suppl. ]

{ }[ Cf. F. trigonométrique. ] Of or pertaining to trigonometry; performed by the rules of trigonometry. [ 1913 Webster ]

--Trig`o*no*met"ric*al*ly, adv. [1913 Webster]

Trigonometrical curve, a curve one of whose coordinates is a trigonometric function of the other. --
Trigonometrical function. See under Function. --
Trigonometrical lines, lines which are employed in solving the different cases of plane and spherical trigonometry, as sines, tangents, secants, and the like. These lines, or the lengths of them, are trigonometrical functions of the arcs and angles to which they belong. --
Trigonometrical survey. See under Survey. [1913 Webster]

n.; pl. -tries [ Gr. &unr_; a triangle + -metry: cf. F. trigonométrie. See Trigon. ] 1. That branch of mathematics which treats of the relations of the sides and angles of triangles, which the methods of deducing from certain given parts other required parts, and also of the general relations which exist between the trigonometrical functions of arcs or angles. [ 1913 Webster ]

2. A treatise in this science. [ 1913 Webster ]

Analytical trigonometry, that branch of trigonometry which treats of the relations and properties of the trigonometrical functions. --
Plane trigonometry, and
Spherical trigonometry, those branches of trigonometry in which its principles are applied to plane triangles and spherical triangles respectively. [ 1913 Webster ]

a. [ L. trigonus, Gr. &unr_;. See Trigon. ] Same as Trigonal. [ 1913 Webster ]