Tris*oc`ta*he"dron (?), *n.* [Gr. ? thrice +
FE. *octahedron*.] *(Crystallog.)* A solid of the isometric
system bounded by twenty-four equal faces, three corresponding to each face
of an octahedron.

**Tetragonal trisoctahedron**, a trisoctahedron each
face of which is a quadrilateral; called also *trapezohedron* and
*icositetrahedron*. -- **Trigonal trisoctahedron**,
a trisoctahedron each face of which is an isosceles triangle.