(Ezek. 1:22, with the epithet "terrible, " as dazzling the spectators with its brightness). The word occurs in Revelation 4:6; 21:11; 22:1. It is a stone of the flint order, the most refined kind of quartz. The Greek word here used means also literally "ice." The ancients regarded the crystal as only pure water congealed into extreme hardness by great length of time.

Noah Webster's New International Dictionary of the English Language

1. (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.

2. (n.) The material of quartz, in crystallization transparent or nearly so, and either colorless or slightly tinged with gray, or the like; -- called also rock crystal. Ornamental vessels are made of it. Cf. Smoky quartz, Pebble; also Brazilian pebble, under Brazilian.

3. (n.) A species of glass, more perfect in its composition and manufacture than common glass, and often cut into ornamental forms. See Flint glass.

4. (n.) The glass over the dial of a watch case.

5. (n.) Anything resembling crystal, as clear water, etc.

6. (a.) Consisting of, or like, crystal; clear; transparent; lucid; pellucid; crystalline.