Definition:Tetrahedron/Regular

Definition
A regular tetrahedron is a tetrahedron whose $4$ faces are all congruent equilateral triangles.

The regular tetrahedron is an example of a deltahedron.

Also known as
It is commonplace for authors to refer to a regular tetrahedron as just a tetrahedron, glossing over the fact of its regularity.

Also see

 * Definition:Platonic Solid
 * Definition:Deltahedron