在几何学中，六面体是指由六个面组成的多面体，而由六个全等的正方形组成的六面体称为正方体。

六个面的多面体可以是正方体、四角柱、五角锥、双三角锥、三方偏方面体。

六个面都是矩形的六面体称为长方体，长方体具有每个二面角相等和每个三面角相等等特性。

A hexahedron (plural: hexahedra) is any polyhedron with six faces. A cube, for example, is a regular hexahedron with all its faces square, and three squares around each vertex.

There are seven topologically distinct convex hexahedra, one of which exists in two mirror image forms. (Two polyhedra are "topologically distinct" if they have intrinsically different arrangements of faces and vertices, such that it is impossible to distort one into the other simply by changing the lengths of edges or the angles between edges or faces.)