The Collaborative International Dictionary of English v.0.48:

Compound \Com"pound\, a. [OE. compouned, p. p. of compounen. See
   Compound, v. t.]
   Composed of two or more elements, ingredients, parts;
   produced by the union of several ingredients, parts, or
   things; composite; as, a compound word.
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         Compound substances are made up of two or more simple
         substances.                              --I. Watts.
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   Compound addition, subtraction, multiplication,
   division (Arith.), the addition, subtraction, etc., of
      compound numbers.

   Compound crystal (Crystallog.), a twin crystal, or one
      seeming to be made up of two or more crystals combined
      according to regular laws of composition.

   Compound engine (Mech.), a form of steam engine in which
      the steam that has been used in a high-pressure cylinder
      is made to do further service in a larger low-pressure
      cylinder, sometimes in several larger cylinders,
      successively.

   Compound ether. (Chem.) See under Ether.

   Compound flower (Bot.), a flower head resembling a single
      flower, but really composed of several florets inclosed in
      a common calyxlike involucre, as the sunflower or
      dandelion.

   Compound fraction. (Math.) See Fraction.

   Compound fracture. See Fracture.

   Compound householder, a householder who compounds or
      arranges with his landlord that his rates shall be
      included in his rents. [Eng.]

   Compound interest. See Interest.

   Compound larceny. (Law) See Larceny.

   Compound leaf (Bot.), a leaf having two or more separate
      blades or leaflets on a common leafstalk.

   Compound microscope. See Microscope.

   Compound motion. See Motion.

   Compound number (Math.), one constructed according to a
      varying scale of denomination; as, 3 cwt., 1 qr., 5 lb.;
      -- called also denominate number.

   Compound pier (Arch.), a clustered column.

   Compound quantity (Alg.), a quantity composed of two or
      more simple quantities or terms, connected by the sign +
      (plus) or - (minus). Thus, a + b - c, and bb - b, are
      compound quantities.

   Compound radical. (Chem.) See Radical.

   Compound ratio (Math.), the product of two or more ratios;
      thus ab:cd is a ratio compounded of the simple ratios a:c
      and b:d.

   Compound rest (Mech.), the tool carriage of an engine
      lathe.

   Compound screw (Mech.), a screw having on the same axis two
      or more screws with different pitch (a differential
      screw), or running in different directions (a right and
      left screw).

   Compound time (Mus.), that in which two or more simple
      measures are combined in one; as, 6-8 time is the joining
      of two measures of 3-8 time.

   Compound word, a word composed of two or more words;
      specifically, two or more words joined together by a
      hyphen.
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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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