'Exterior angle' definitions:

Definition of 'exterior angle'

noun

The supplement of an interior angle of a polygon [syn: exterior angle, external angle]

From: GCIDE

Exterior \Ex*te"ri*or\, a. [L. exterior, compar. of exter or exterus on the outside, outward, foreign, strange, a compar. fr. ex: cf. F. ext['e]rieur. See Ex-, and cf. Extreme, Interior.]
1. External; outward; pertaining to that which is external; -- opposed to interior; as, the exterior part of a sphere. [1913 Webster]
Sith nor the exterior nor the inward man Resemble that it was. --Shak. [1913 Webster]
2. External; on the outside; without the limits of; extrinsic; as, an object exterior to a man, opposed to what is within, or in his mind. [1913 Webster]
Without exterior help sustained. --Milton. [1913 Webster]
3. Relating to foreign nations; foreign; as, the exterior relations of a state or kingdom. [1913 Webster]
Exterior angle (Geom.), the angle included between any side of a triangle or polygon and the prolongation of the adjacent side; also, an angle included between a line crossing two parallel lines and either of the latter on the outside.
Exterior side (Fort.), the side of the polygon upon which a front of fortification is formed. --Wilhelm. [1913 Webster]
Note: See Illust. of Ravelin. [1913 Webster]