crystal

n. 1 a transparent colourless mineral, esp. Rock crystal. B piece of this. 2 a highly transparent glass; flint glass. B articles of this. 3 crystalline piece of semiconductor. 4 aggregation of molecules with a definite internal structure and the external form of a solid enclosed by symmetrically arranged plane faces. adj. (usu. Attrib.) Made of, like, or clear as crystal. [greek krustallos]

n. The regular form which a substance tends to assume in solidifying, through the inherent power of cohesive attraction. It is bounded by plane surfaces, symmetrically arranged, and each species of crystal has fixed axial ratios. See Crystallization.