
polyhedron


A threedimensional figure bounded by plane polygonal faces. The point at which three or more faces meet is called a vertex. A line along which two faces meet is called an edge.
A regular polyhedron is a polyhedron all of whose faces are congruent regular polygons. There are only five regular polyhedrons, and they are the regular tetrahedron (four equilateral triangular faces), the regular hexahedron (cube), the regular octahedron (eight equilateral triangular faces), the regular dodecahedron (twelve regular pentagonal faces), and the regular icosahedron (twenty equilateral triangular faces).

