crystal in WordNet English dictionary

1. a protective cover that protects the face of a watch
   crystal  watch crystal  watch glass 
   
2. glassware made of quartz
   crystal 
   
3. a crystalline element used as a component in various electronic devices
   crystal 
   
4. a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces
   crystal  crystallization 
   
5. a solid formed by the solidification of a chemical and having a highly regular atomic structure
   crystal 
   
6. colorless glass made of almost pure silica
   quartz glass  quartz  vitreous silica  lechatelierite  crystal