Tĕt'ra-hē'dral, a.

[See TETRAHEDRON.] 1. Having, or composed of, four sides. 2. (Crystallog.) (a.) Having the form of the regular tetrahedron. (b.) Pertaining or related to a tetrahedron, or to the system of forms to which the tetrahedron belongs.

Tetrahedral angle (Geom.), a solid angle bounded or inclosed by four plane angles. Math. Dict.