Source : Webster's Revised Unabridged Dictionary (1913)
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
difference are 1. See {Figurate numbers}, under
{Figurate}.