The Collaborative International Dictionary
Deltohedron
Deltohedron \Del`to*he"dron\, n. [Gr. de`lta, the letter [Delta] + 'e`dra seat, base.] (Crystallog.) A solid bounded by twelve quadrilateral faces. It is a hemihedral form of the isometric system, allied to the tetrahedron.
Wiktionary
deltohedron
n. The dual polyhedron of a regular ''n''-sided antiprism.