Definition:Octahedron/Regular

Definition
A regular octahedron is an octahedron whose $8$ faces are all congruent equilateral triangles.

The regular octahedron is an example of a deltahedron.

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

Also see

 * Definition:Platonic Solid
 * Definition:Deltahedron