The Collaborative International Dictionary of English v.0.48:

Rock \Rock\, n. [OF. roke, F. roche; cf. Armor. roc'h, and AS.
   rocc.]
   1. A large concreted mass of stony material; a large fixed
      stone or crag. See Stone.
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            Come one, come all! this rock shall fly
            From its firm base as soon as I.      --Sir W.
                                                  Scott.
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   2. (Geol.) Any natural deposit forming a part of the earth's
      crust, whether consolidated or not, including sand, earth,
      clay, etc., when in natural beds.
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   3. That which resembles a rock in firmness; a defense; a
      support; a refuge.
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            The Lord is my rock, and my fortress. --2 Sam. xxii.
                                                  2.
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   4. Fig.: Anything which causes a disaster or wreck resembling
      the wreck of a vessel upon a rock.
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   5. (Zool.) The striped bass. See under Bass.
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   Note: This word is frequently used in the formation of
         self-explaining compounds; as, rock-bound, rock-built,
         rock-ribbed, rock-roofed, and the like.
         [1913 Webster]

   Rock alum. [Probably so called by confusion with F. roche a
      rock.] Same as Roche alum.

   Rock barnacle (Zool.), a barnacle (Balanus balanoides)
      very abundant on rocks washed by tides.

   Rock bass. (Zool.)
      (a) The stripped bass. See under Bass.
      (b) The goggle-eye.
      (c) The cabrilla. Other species are also locally called
          rock bass.

   Rock builder (Zool.), any species of animal whose remains
      contribute to the formation of rocks, especially the
      corals and Foraminifera.

   Rock butter (Min.), native alum mixed with clay and oxide
      of iron, usually in soft masses of a yellowish white
      color, occuring in cavities and fissures in argillaceous
      slate.

   Rock candy, a form of candy consisting of crystals of pure
      sugar which are very hard, whence the name.

   Rock cavy. (Zool.) See Moco.

   Rock cod (Zool.)
      (a) A small, often reddish or brown, variety of the cod
          found about rocks andledges.
      (b) A California rockfish.

   Rock cook. (Zool.)
      (a) A European wrasse (Centrolabrus exoletus).
      (b) A rockling.

   Rock cork (Min.), a variety of asbestus the fibers of which
      are loosely interlaced. It resembles cork in its texture.


   Rock crab (Zool.), any one of several species of large
      crabs of the genus C, as the two species of the New
      England coast (Cancer irroratus and Cancer borealis).
      See Illust. under Cancer.

   Rock cress (Bot.), a name of several plants of the cress
      kind found on rocks, as Arabis petraea, Arabis lyrata,
      etc.

   Rock crystal (Min.), limpid quartz. See Quartz, and under
      Crystal.

   Rock dove (Zool.), the rock pigeon; -- called also rock
      doo.

   Rock drill, an implement for drilling holes in rock; esp.,
      a machine impelled by steam or compressed air, for
      drilling holes for blasting, etc.

   Rock duck (Zool.), the harlequin duck.

   Rock eel. (Zool.) See Gunnel.

   Rock goat (Zool.), a wild goat, or ibex.

   Rock hopper (Zool.), a penguin of the genus Catarractes.
      See under Penguin.

   Rock kangaroo. (Zool.) See Kangaroo, and Petrogale.

   Rock lobster (Zool.), any one of several species of large
      spinose lobsters of the genera Panulirus and
      Palinurus. They have no large claws. Called also spiny
      lobster, and sea crayfish.

   Rock meal (Min.), a light powdery variety of calcite
      occuring as an efflorescence.

   Rock milk. (Min.) See Agaric mineral, under Agaric.

   Rock moss, a kind of lichen; the cudbear. See Cudbear.

   Rock oil. See Petroleum.

   Rock parrakeet (Zool.), a small Australian parrakeet
      (Euphema petrophila), which nests in holes among the
      rocks of high cliffs. Its general color is yellowish olive
      green; a frontal band and the outer edge of the wing
      quills are deep blue, and the central tail feathers bluish
      green.

   Rock pigeon (Zool.), the wild pigeon (Columba livia) Of
      Europe and Asia, from which the domestic pigeon was
      derived. See Illust. under Pigeon.

   Rock pipit. (Zool.) See the Note under Pipit.

   Rock plover. (Zool.)
      (a) The black-bellied, or whistling, plover.
      (b) The rock snipe.

   Rock ptarmigan (Zool.), an arctic American ptarmigan
      (Lagopus rupestris), which in winter is white, with the
      tail and lores black. In summer the males are grayish
      brown, coarsely vermiculated with black, and have black
      patches on the back.

   Rock rabbit (Zool.), the hyrax. See Cony, and Daman.

   Rock ruby (Min.), a fine reddish variety of garnet.

   Rock salt (Min.), cloride of sodium (common salt) occuring
      in rocklike masses in mines; mineral salt; salt dug from
      the earth. In the United States this name is sometimes
      given to salt in large crystals, formed by evaporation
      from sea water in large basins or cavities.

   Rock seal (Zool.), the harbor seal. See Seal.

   Rock shell (Zool.), any species of Murex, Purpura, and
      allied genera.

   Rock snake (Zool.), any one of several large pythons; as,
      the royal rock snake (Python regia) of Africa, and the
      rock snake of India (Python molurus). The Australian
      rock snakes mostly belong to the allied genus Morelia.


   Rock snipe (Zool.), the purple sandpiper (Tringa
      maritima); -- called also rock bird, rock plover,
      winter snipe.

   Rock soap (Min.), a kind of clay having a smooth, greasy
      feel, and adhering to the tongue.

   Rock sparrow. (Zool.)
      (a) Any one of several species of Old World sparrows of
          the genus Petronia, as Petronia stulla, of Europe.
      (b) A North American sparrow (Pucaea ruficeps).

   Rock tar, petroleum.

   Rock thrush (Zool.), any Old World thrush of the genus
      Monticola, or Petrocossyphus; as, the European rock
      thrush (Monticola saxatilis), and the blue rock thrush
      of India (Monticola cyaneus), in which the male is blue
      throughout.

   Rock tripe (Bot.), a kind of lichen (Umbilicaria
      Dillenii) growing on rocks in the northen parts of
      America, and forming broad, flat, coriaceous, dark fuscous
      or blackish expansions. It has been used as food in cases
      of extremity.

   Rock trout (Zool.), any one of several species of marine
      food fishes of the genus Hexagrammus, family Chiradae,
      native of the North Pacific coasts; -- called also sea
      trout, boregat, bodieron, and starling.

   Rock warbler (Zool.), a small Australian singing bird
      (Origma rubricata) which frequents rocky ravines and
      water courses; -- called also cataract bird.

   Rock wren (Zool.), any one of several species of wrens of
      the genus Salpinctes, native of the arid plains of Lower
      California and Mexico.
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The Collaborative International Dictionary of English v.0.48:

Crystal \Crys"tal\ (kr[i^]s"tal), n. [OE. cristal, F. cristal,
   L. crystallum crystal, ice, fr. Gr. kry`stallos, fr. kry`os
   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.
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   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.
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   3. A species of glass, more perfect in its composition and
      manufacture than common glass, and often cut into
      ornamental forms. See Flint glass.
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   4. The glass over the dial of a watch case.
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   5. Anything resembling crystal, as clear water, etc.
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            The blue crystal of the seas.         --Byron.
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   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.
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WordNet (r) 3.0 (2006):

rock crystal
    n 1: a clear quartz used in making electronic and optical
         equipment [syn: rock crystal, transparent quartz]