Tetrahedron
Pronunciation : Tet`ra*he"dron
Part of Speech : n.
Etymology : [Tetra- + Gr. (Geom.)
Definition : Defn: A solid figure inclosed or bounded by four triangles.
Note: In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron. Regular tetrahedron (Geom.), a solid bounded by four equal equilateral triangles; one of the five regular solids.
Source : Webster's Unabridged Dictionary, 1913