Antiprism

In geometry, an $n$ -gonal antiprism or $n$ -antiprism is a polyhedron composed of two parallel direct copies (not mirror images) of an $n$ -sidedpolygon, connected by an alternating band of $2 n$ triangles. They are represented by the Conway notation $A n$ .

Antiprisms are a subclass of prismatoids, and are a (degenerate) type of snub polyhedron.

Antiprisms are similar to prisms, except that the bases are twisted relatively to each other, and that the side faces (connecting the bases) are $2 n$ triangles, rather than $n$ quadrilaterals.

The dual polyhedron of an $n$ -gonal antiprism is an $n$ -gonal trapezohedron.