Geom. and Cryst. [f. TRIS- + TETRAHEDRON.] A solid figure having 12 faces, every three of which correspond to one face of a tetrahedron: either with triangular faces (= triakistetrahedron), or with trapezoidal faces. (Cf. TRISOCTAHEDRON.)
1890. W. G. Huntington, Elem. Cryst., 76. So the trigonal tristetrahedron oscillates between the tetrahedron and the cube; and the tetragonal tristetrahedron, between the tetrahedron and rhombic dodecahedron.
