Irregular tetrahedron

An irregular tetrahedron is a tetrahedron with no symmetries. Generally, though not necessarily, it has four different scalene triangles for faces.

In vertex figures
A total of 17 uniform polychora, including the convex great disprismatotesseractihexadecachoron and great disprismatohexacosihecatonicosachoron, have irregular tetrahedra for cells. These are known as omnitruncaates or maximized polychora and have the most vertices possible to be uniform in their symmetry.