disphenoid

noun

di·sphenoid | \ (ˈ)dī+\

Definition of disphenoid

1 : a wedge-shaped crystal form of the tetragonal or orthorhombic system having four like triangular faces that correspond in position to alternate faces of the tetragonal or orthorhombic dipyramid and being symmetrical about each of three mutually perpendicular diad axes of symmetry in all classes except the tetragonal-disphenoidal in which the form is generated by an inverse tetrad axis of symmetry

2 : a form of crystal bounded by eight scalene triangles arranged in pairs : the tetragonal scalenohedron