A toroidal solid, or toroid, is an orientable polyhedron without self-intersections that has genus greater than zero, meaning that it contains one or more holes. An orientable polyhedron's genus (G) is related to the number of vertices (V), faces (F), and edges (E) as follows:

V + F − E = 2 − 2 * G

A toroid is said to be non-regular if not all of its faces have the same number of vertices, or not all of its vertices join the same number of faces. All of the toroids on this page are non-regular.