Definition:Icosahedron

Definition
An icosahedron is a polyhedron which has $20$ faces.

Linguistic Note
The word icosahedron derives from the Classical Greek εἰκοσάεδρον:


 * eíkosi (εἴκοσι), meaning twenty
 * hedron (a form of ἕδρα), meaning base or seat.

The technically correct plural of icosahedron is icosahedra, but the word icosahedrons can often be found.