Source : Webster's Revised Unabridged Dictionary (1913)

Crystal \Crys"tal\ (kr?s"tal), n. [OE. cristal, F. cristal, L.
   crystallum crystal, ice, fr. Gr. ????, fr. ???? icy cold,
   frost; cf. AS. crystalla, fr. L. crystallum; prob. akin to E.
   crust. See {Crust}, {Raw}.]
   1. (Chem. & Min.) The regular form which a substance tends to
      assume in solidifying, through the inherent power of
      cohesive attraction. It is bounded by plane surfaces,
      symmetrically arranged, and each species of crystal has
      fixed axial ratios. See {Crystallization}.

   2. The material of quartz, in crystallization transparent or
      nearly so, and either colorless or slightly tinged with
      gray, or the like; -- called also {rock crystal}.
      Ornamental vessels are made of it. Cf. {Smoky quartz},
      {Pebble}; also {Brazilian pebble}, under {Brazilian}.

   3. A species of glass, more perfect in its composition and
      manufacture than common glass, and often cut into
      ornamental forms. See {Flint glass}.

   4. The glass over the dial of a watch case.

   5. Anything resembling crystal, as clear water, etc.

            The blue crystal of the seas.         --Byron.

   {Blood crystal}. See under {Blood}.

   {Compound crystal}. See under {Compound}.

   {Iceland crystal}, a transparent variety of calcite, or
      crystallized calcium carbonate, brought from Iceland, and
      used in certain optical instruments, as the polariscope.
      

   {Rock crystal}, or {Mountain crystal}, any transparent
      crystal of quartz, particularly of limpid or colorless
      quartz.

Crystal \Crys"tal\, a.
   Consisting of, or like, crystal; clear; transparent; lucid;
   pellucid; crystalline.

         Through crystal walls each little mote will peep.
                                                  --Shak.

         By crystal streams that murmur through the meads.
                                                  --Dryden.

         The crystal pellets at the touch congeal, And from the
         ground rebounds the ratting hail.        --H. Brooks.

Source : WordNet®

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

Source : Free On-Line Dictionary of Computing

Crystal
     
        Concurrent Representation of Your Space-Time ALgorithms.
     
        A {recursion equation} parallel language.
     
        ["A Parallel Language and its Compilation to Multiprocessor
        Machines or VLSI", M.C. Chen, 13th POPL, ACM 1986 pp.131-139].
     
        (1994-12-06)