| tetrahedron | <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. <geometry> Regular tetrahedron, a solid bounded by four equal equilateral triangles; one of the five regular solids. Origin: Tetra- + Gr. Seat, base, fr. To sit. Source: Websters Dictionary (01 Mar 1998) |
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