有四面的,四面體的
Tetrahedral \Tet`ra*he"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 hemihedral forms to which the tetrahedron belongs. {Tetrahedral angle} (Geom.), a solid angle bounded or inclosed by four plane angles.