Definition:Tetrahedron

Definition
A tetrahedron is a polyhedron which has $4$ faces.

Linguistic Note
The word tetrahedron derives from the Classical Greek τετράεδρόν:


 * tetrás (τετράς), meaning four
 * hedron (a form of ἕδρα), meaning base or seat.

The technically correct plural of tetrahedron is tetrahedra, but the word tetrahedrons can often be found.