■ noun
1》 a piece of a homogeneous solid substance having a natural geometrically regular form with symmetrically arranged plane faces.
↘ Chemistry any solid consisting of a symmetrical, ordered, three-dimensional aggregation of atoms or molecules.
↘a clear transparent mineral, especially quartz.
2》 (also ~ glass ) highly transparent glass with a high refractive index.
↘the glass over a watch face.
3》 [as modifier ] clear and transparent: the ~ waters of the lake.
Origin
OE (denoting ice or a mineral resembling it), from OFr. cristal , from L. ~lum , from Gk krustallos 'ice, ~'.