Polychoron

A polychoron (pronounced /ˌpɒliˈkɔːɹɒn/, or more rarely /-ˈxɔːɹɒn/) or 4-polytope is a four-dimensional polytope. The facets of polychora are three-dimensional polyhedra, which are called its cells. There are six convex regular polychora, ten non-convex regular polychora, and infinitely many uniform polychora.