Source : Webster's Revised Unabridged Dictionary (1913)

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.

            Sith nor the exterior nor the inward man Resemble
            that it was.                          --Shak.

   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.

            Without exterior help sustained.      --Milton.

   3. Relating to foreign nations; foreign; as, the exterior
      relations of a state or kingdom.

   {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.

   Note: See Illust. of {Ravelin}.

Source : WordNet®

exterior angle
     n : the supplement of an interior angle of a polygon [syn: {external
         angle}]