DICT.TW Dictionary Taiwan

 Tet·ra·he·dron n.  Geom. A solid figure inclosed or bounded by four triangles.
 Note: ☞ In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron.
 Regular tetrahedron Geom., a solid bounded by four equal equilateral triangles; one of the five regular solids.
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 regular tetrahedron
      n : a tetrahedron with four equilateral triangular faces