crystal

n. & adj.
—n.
1 a a clear transparent mineral, esp. rock crystal. b a piece of this.
2 (in full crystal glass) a highly transparent glass; flint glass. b articles made of this.
3 the glass over a watch-face.
4 Electronics a crystalline piece of semiconductor.
5 Chem. a an aggregation of molecules with a definite internal structure and the external form of a solid enclosed by symmetrically arranged plane faces. b a solid whose constituent particles are symmetrically arranged.
—adj. (usu. attrib.) made of, like, or clear as crystal.
Phrases and idioms:
crystal ball a glass globe used in crystal-gazing. crystal class Crystallog. any of 32 categories of crystals classified according to their symmetry. crystal clear unclouded, transparent. crystal-gazing the process of concentrating one's gaze on a crystal ball supposedly in order to obtain a picture of future events etc. crystal lattice Crystallog. the regular repeating pattern of atoms, ions, or molecules in a crystalline substance. crystal set a simple early form of radio receiving apparatus with a crystal touching a metal wire as the rectifier. crystal system Crystallog. any of seven possible unique combinations of unit cells, crystal lattices, and symmetry elements of a crystal class.
Etymology: OE f. OF cristal f. L crystallum f. Gk krustallos ice, crystal