Crystal

n. [Lat. crystallum, Gr. κρύσταλλος, ice, crystal, from κρύος, icy cold, frost; Fr., Pr., & Sp. cristal, It. cristallo, Ger. krystall, A.-S. cristalla.]

1. (Chem. & Min.) 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. Dana.
2. A species of glass, more perfect in its composition and manufacture than common glass.
3. The glass of a watch-case.
4. Any thing resembling crystal, as clear water, &c. “The trembling groves, the crystal running by.” Spenser.

Iceland crystal, a transparent variety of calcareous spar, or crystallized carbonate of lime, brought from Iceland, and remarkable for its double refraction. — Rock crystal, or mountain crystal, any transparent crystal of quartz, particularly of limpid or colorless quartz.