(mineralogy) A mineral crystal whose interior space is empty

plural of crystal dick

(uncountable, idiomatic, slang) Erectile dysfunction caused by methamphetamine use or other drug use.

(now historical) Crystal; a piece of crystal.

(crystallography) Any of the seven distinct symmetry classifications of crystals: cubic, tetragonal, hexagonal, orthorhombic, monoclinic, triclinic and trigonal.

A small crystal from which a larger crystal of the same substance is grown

In a crystal clear manner

crystal clear

A periodic optical nanostructure that affects the motion of photons in much the same way that ionic lattices affect electrons in solids.

Glass that contains at least 24% lead oxide (PbO). / Cut glass made of this material.