# Definition:Dodecahedron/Regular

## Definition

A regular dodecahedron is a dodecahedron whose $12$ faces are all congruent regular pentagons.

It has:

## Historical Note

In The Elements, this object is referred to just as a dodecahedron.

In the words of Euclid:

A dodecahedron is a solid figure contained by twelve equal, equilateral, and equiangular pentagons.

According to the Pythagorean tradition, the regular dodecahedron was the symbol associated with the sphere of the fixed stars, and later with the quintessence of the medieval alchemists.

## Linguistic Note

The word dodecahedron derives from the Classical Greek δωδεκάεδρόν:

dodeca (δωδεκά), meaning twelve
hedron (a form of ἕδρα), meaning base or seat.

The technically correct plural of dodecahedron is dodecahedra, but the word dodecahedrons can often be found.