from The Century Dictionary and Cyclopedia
- In crystallography: Twice four-angled or twice four-sided: said of the eight-faced prism and eight-faced pyramid (or double pyramid) of the tetragonal system.
- Noting a type of symmetry characterized by a tetrad axis (that is, one of tetragonal or fourfold symmetry) in which four planes of symmetry intersect. See symmetry.
Sorry, no etymologies found.