# Definition:Polyhedron

## Definition

A **polyhedron** is a three-dimensional figure that is contained by polygonal faces.

### Face

The **faces** of a polyhedron are the polygons which contain it.

### Edge

The **edges** of a polyhedron are the sides of the polygons which constitute its faces.

### Vertex

The **vertices** of a polyhedron are the vertices of the polygons which constitute its faces.

## Linguistic Note

The word **polyhedron** comes directly from the Classical Greek **πολύεδρον**:

**polys**(**πολύς**), meaning**many****hedron**(a form of**ἕδρα**), meaning**base**or**seat**.

The technically correct plural of **polyhedron** is **polyhedra**, but the word **polyhedrons** can often be found.

## Sources

- 1992: George F. Simmons:
*Calculus Gems*... (previous) ... (next): Chapter $\text {A}.4$: Euclid (flourished ca. $300$ B.C.)