\Do*dec`a*he"dron\, n. [Gr. ?; ? twelve + ? seat, bottom, base: cf. F. dod['e]ca[`e]dre.] (Geom. & Crystallog.) A solid having twelve faces. Note: The regular dodecahedron is bounded by twelve equal and regular pentagons; the pyritohedron (see {Pyritohedron}) is related to it; the rhombic dodecahedron is bounded by twelve equal rhombic faces.