Com·pound a.  Composed of two or more elements, ingredients, parts; produced by the union of several ingredients, parts, or things; composite; as, a compound word.
    Compound substances are made up of two or more simple substances.   --I. Watts.
 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.
 Crys·tal n.
 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.