Ditope

A ditope is a polytope with two facets. Most definitions of polytopes require the two facets of the ditope to be identical, making ditopes generally degenerate. The sole exception is the dyad which can be considered as a rank-1 ditope and is non-degenerate.

The ditope of a convex polytope can be modeled as a tiling of an $n$-sphere without coincident facets. If the facets of divide the $n$-sphere as an equator, each half of the $n$-sphere then can each serve as the interior of one of the ditope's facets.

The dual of a ditope is a hosotope.