Tetrahedron
Tetrahedron , noun
[Tetra- + Greek {not transcribed} seat, base, from {not transcribed} to sit.]
(Geometry) A solid figure inclosed or bounded by four triangles.
In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron.
Collocations (1)
Regular tetrahedron (Geometry) , a solid bounded by four equal equilateral triangles; one of the five regular solids.