Definition of "disphenoid" in English

adjective

1. (mineralogy) Of or pertaining to a wedge-shaped crystal form of the tetragonal or orthorhombic system.

2. (mineralogy) Of or pertaining to a crystal form bounded by eight scalene triangles arranged in pairs, constituting a tetragonal scalenohedron.

noun

1. (geometry) A non-regular tetrahedron whose four faces are congruent acute-angled triangles.

   • 1973, H. S. M. Coxeter, 3rd Edition, unnumbered page, To make a model of a disphenoid, cut out an acute angled triangle and fold it along the joins of the mid-points of the sides. The disphenoid is said to be rhombic or tetragonal according as the triangle is isosceles or scalene.