OCTAHEDRON (Gr. omo, eight, fdpa, base), a solid bounded by eight triangular faces; it has 6 vertices and 12 edges. The regular octahedron has for its faces equilateral triangles; it is the reciprocal of the cube. Octahedra having triangular faces other than equilateral occur as crystal forms. See Polyhedron and Crystallography.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)