Search Result for "icosahedron": 
Wordnet 3.0

NOUN (1)

1. any polyhedron having twenty plane faces;

The Collaborative International Dictionary of English v.0.48:

Icosahedron \I`co*sa*he"dron\, n. [Gr. ?; ? twenty + ? seat, base, fr. ? to sit.] (Geom.) A solid bounded by twenty sides or faces. [1913 Webster] Regular icosahedron, one of the five regular polyhedrons, bounded by twenty equilateral triangules. Five triangles meet to form each solid angle of the polyhedron. [1913 Webster]
WordNet (r) 3.0 (2006):

icosahedron n 1: any polyhedron having twenty plane faces