Found 2 items, similar to tetrahedron.
English → English (WordNet) Definition: tetrahedron tetrahedron n : any polyhedron having four plane faces [also: tetrahedra (pl)]
English → English (gcide) Definition: Tetrahedron Tetrahedron \Tet`ra*he"dron\, n. [Tetra- + Gr. ? seat, base, fr. ? to sit.] (Geom.) A solid figure inclosed or bounded by four triangles. [1913 Webster] Note: In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron. [1913 Webster] Regular tetrahedron (Geom.), a solid bounded by four equal equilateral triangles; one of the five regular solids. [1913 Webster]