1.  crystal(n = noun.substance) Array - a solid formed by the solidification of a chemical and having a highly regular atomic structure; Array
is a kind of solid
has particulars: flake, snowflake, diamond dust, frost mist, frost snow, ice crystal, ice needle, poudrin, snow mist, gem, gemstone, stone, twins, ice, water ice
Derived forms verb crystalize₃, verb crystalize₂, verb crystallize₄, verb crystallize₃

2.  crystal(n = noun.artifact) Array - a crystalline element used as a component in various electronic devices; Array
is a kind of component, constituent, element
is a part of crystal counter, crystal detector, crystal microphone, crystal pickup
has particulars: piezoelectric crystal

3.  crystal(n = noun.object) crystallization - a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces; Array
is a kind of rock, stone
has particulars: crystallite
Derived forms verb crystalize₃, verb crystalize₂

4.  crystal(n = noun.substance) lechatelierite, quartz, quartz glass, vitreous silica - colorless glass made of almost pure silica; Array
is a kind of natural glass
Derived forms verb crystalize₃, verb crystalize₂, verb crystallize₄, verb crystallize₃

5.  crystal(n = noun.artifact) Array - glassware made of quartz; Array
is a kind of glassware, glasswork

6.  crystal(n = noun.artifact) watch crystal, watch glass - a protective cover that protects the face of a watch; Array
is a kind of protection, protective cover, protective covering
is a part of ticker, watch

1.  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. [1913 Webster]

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. [1913 Webster]

3.  A species of glass, more perfect in its composition and manufacture than common glass, and often cut into ornamental forms. See Flint glass. [1913 Webster]

4.  The glass over the dial of a watch case. [1913 Webster]

5.  Anything resembling crystal, as clear water, etc. [1913 Webster]
"The blue crystal of the seas." [1913 Webster]

   Consisting of, or like, crystal; clear; transparent; lucid; pellucid; crystalline. [1913 Webster]
"Through crystal walls each little mote will peep." [1913 Webster]
"By crystal streams that murmur through the meads." [1913 Webster]
"The crystal pellets at the touch congeal,
And from the ground rebounds the ratting hail." [1913 Webster]

crystal, n. & adj.
--n.
1 a a clear transparent mineral, esp. rock crystal. b a piece of this.
2 (in full crystal glass) a highly transparent glass; flint glass. b articles made of this.
3 the glass over a watch-face.
4 Electronics a crystalline piece of semiconductor.
5 Chem. a an aggregation of molecules with a definite internal structure and the external form of a solid enclosed by symmetrically arranged plane faces. b a solid whose constituent particles are symmetrically arranged.
--adj. (usu. attrib.) made of, like, or clear as crystal.

Idiom:
crystal ball a glass globe used in crystal-gazing. crystal class Crystallog. any of 32 categories of crystals classified according to their symmetry. crystal clear unclouded, transparent. crystal-gazing the process of concentrating one's gaze on a crystal ball supposedly in order to obtain a picture of future events etc. crystal lattice Crystallog. the regular repeating pattern of atoms, ions, or molecules in a crystalline substance. crystal set a simple early form of radio receiving apparatus with a crystal touching a metal wire as the rectifier. crystal system Crystallog. any of seven possible unique combinations of unit cells, crystal lattices, and symmetry elements of a crystal class.

Etymology:
OE f. OF cristal f. L crystallum f. Gk krustallos ice, crystal

N  hardness, rigidity, renitence, renitency, inflexibility, temper, callosity, durity, induration, petrifaction, lapidification, lapidescence, vitrification, ossification, crystallization, stone, pebble, flint, marble, rock, fossil, crag, crystal, quartz, granite, adamant, bone, cartilage, hardware, heart of oak, block, board, deal board, iron, steel, cast iron, decarbonized iron, wrought iron, nail, brick, concrete, cement, hard, rigid, stubborn, stiff, firm, starch, starched, stark, unbending, unlimber, unyielding, inflexible, tense, indurate, indurated, gritty, proof, adamant, adamantine, adamantean, concrete, stony, granitic, calculous, lithic, vitreous, horny, corneous, bony, osseous, ossific, cartilaginous, hard as a rock, stiff as buckram, stiff as a poker, stiff as starch, stiff as as board.

N  transparence, transparency, clarity, translucence, translucency, diaphaneity, lucidity, pellucidity, limpidity, fluorescence, transillumination, translumination, transparent medium, glass, crystal, lymph, vitrite, water, transparent, pellucid, lucid, diaphanous, translucent, tralucent, relucent, limpid, clear, serene, crystalline, clear as crystal, vitreous, transpicuous, glassy, hyaline, hyaloid, vitreform.

crystal ball, crystal clear, crystal counter, crystal detector, crystal gazer, crystal gazing, crystal lattice, crystal microphone, crystal oscillator, crystal pickup, crystal rectifier, crystal set, crystal tea, crystal violet, ice crystal, liquid crystal, liquid crystal display, piezoelectric crystal, quartz crystal, rock crystal, watch crystal