crys·tal (krĭs'təl)
n.

1. 1. A homogenous solid formed by a repeating, three-dimensional pattern of atoms, ions, or molecules and having fixed distances between constituent parts.
   2. The unit cell of such a pattern.
2. A mineral, especially a transparent form of quartz, having a crystalline structure, often characterized by external planar faces.
3. 1. A natural or synthetic crystalline material having piezoelectric or semiconducting properties.
   2. An electronic device, such as an oscillator or detector, using such a material.
4. 1. A high-quality, clear, colorless glass.
   2. An object, especially a vessel or ornament, made of such glass.
   3. Such objects considered as a group.
5. A clear glass or plastic protective cover for the face of a watch or clock.
6. Slang. A stimulant drug, usually methamphetamine, in its powdered form.

adj.
Clear or transparent: a crystal lake; the crystal clarity of their reasoning.

[Middle English cristal, from Old French, from Latin crystallum, from Greek krustallos, ice, crystal.]

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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