A convex polyhedron with two ‘end’ faces that are congruent polygons lying in parallel planes, with each vertex of one polygon joined by an edge to two vertices of the other polygon, so that the remaining faces are triangles. If the end faces are regular, the antiprism is said to be right-regular. If the end faces are regular and the triangular faces are equilateral, the antiprism is a semi-regular polyhedron.