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 (Zo["o]l.), 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

1. See Figurate numbers, under Figurate.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Compasses \Com"pass*es\, n., pl. An instrument for describing circles, measuring figures, etc., consisting of two, or (rarely) more, pointed branches, or legs, usually joined at the top by a rivet on which they move.

Note: The compasses for drawing circles have adjustable pen points, pencil points, etc.; those used for measuring without adjustable points are generally called dividers. See Dividers.

Bow compasses. See Bow-compass.

Caliber compasses, Caliper compasses. See Calipers.

Proportional, Triangular, etc., compasses. See under Proportional, etc.

Source: Webster's Revised Unabridged Dictionary (1913)