ABCDEFGHIJKLMNOPQRSTUVWXYZ Definition of Icosahedron more ... A polyhedron (a flat-sided solid object) with 20 Faces. When it is "regular" (side lengths are equal and angles are equal) it is one of the Platonic Solids Play with one here: ../geometry/images/polyhedra.js?mode=icosahedron See: Polyhedron Spinning Icosahedron
