Glossary of Terms

Dodecahedron

Twelve sided polyhedron with all sides equidimensional and either rhombic or pentagonal. If the dodecahedron is composed of rhombs, it is known as a rhombic dodecahedron, or simply as a dodecahedron. If it is composed of pentagons, it is known as a pentagonal dodecahedron or pyritohedron.
Minerals shaped as dodecahedrons belong to the isometric system.

Both dodecahdra and dodecahedrons are acceptable plural terms.