In Euclidean geometry, a three-dimensional object composed of a finite number of polygonal surfaces (faces). Technically, a polyhedron is the boundary between the interior and exterior of a solid. In general, polyhedrons are named according to number of faces. A tetrahedron has four faces, a pentahedron five, and so on; a cube is a six-sided regular polyhedron (hexahedron) whose faces are squares. The faces meet at line segments called edges, which meet at points called vertices. See also Platonic solid; Euler's formula.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on polyhedron, visit Britannica.com.

Seen & Heard

What made you look up polyhedron? Please tell us what you were reading, watching or discussing that led you here.