octahedron
octahedron (ok`tȧ*hē"dron) , noun
[Greek 'okta`edron, from 'okta`edros eight-sided; 'okta- (for 'oktw` eight) + "e`dra seat, base, from "e`zesqai to sit.]
(Geometry) A solid bounded by eight faces. The regular octahedron is contained by eight equal equilateral triangles.