1. A solid figure comprehended bounded by four equilateral and equal triangles.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• retrahedron,
• fetrahedron,
• getrahedron,
• yetrahedron,
• 6etrahedron,
• 5etrahedron,
• twtrahedron,
• tstrahedron,
• tdtrahedron,
• trtrahedron,
• t4trahedron,
• t3trahedron,
• terrahedron,
• teterahedron,
• tetrahederon,
• tetrahedon,
• teetrahedron,
• tetrahedral,
• Tetrahedran,
• tetrahexhedron

• tetraodontidae.

The adjective form of the word "tetrahedron" is "tetrahedral".