crystal

(noun) a solid formed by the solidification of a chemical and having a highly regular atomic structure.

(noun) a crystalline element used as a component in various electronic devices.

(noun) a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces. Synonyms: crystallization.

(noun) colorless glass made of almost pure silica. Synonyms: quartz glass, quartz, vitreous silica, lechatelierite.

(noun) glassware made of quartz.

(noun) a protective cover that protects the face of a watch. Synonyms: watch crystal, watch glass.