n. [ Gr. 'okta`edron, fr. 'okta`edros eight-sided; 'okta- (for 'oktw` eight) + "e`dra seat, base, from "e`zesqai to sit. ] (Geom.) A solid bounded by eight faces. The regular octahedron is contained by eight equal equilateral triangles. [ 1913 Webster ]