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.


 E·ther n.  [Written also æther.]
 1. Physics A medium of great elasticity and extreme tenuity, once supposed to pervade all space, the interior of solid bodies not excepted, and to be the medium of transmission of light and heat; hence often called luminiferous ether.  It is no longer believed that such a medium is required for the transmission of electromagnetic waves; the modern use of the term is mostly a figurative term for empty space, or for literary effect, and not intended to imply the actual existence of a physical medium.  However. modern cosmological theories based on quantum field theory do not rule out the possibility that the inherent energy of the vacuum is greater than zero, in which case the concept of an ether pervading the vacuum may have more than metaphoric meaning.
 2. Supposed matter above the air; the air itself.
 3. Chem. (a) A light, volatile, mobile, inflammable liquid, (C2H5)2O, of a characteristic aromatic odor, obtained by the distillation of alcohol with sulphuric acid, and hence called also sulphuric ether.  It is a powerful solvent of fats, resins, and pyroxylin, but finds its chief use as an anæsthetic. Commonly called ethyl ether to distinguish it from other ethers, and also ethyl oxide. (b) Any similar compound in which an oxygen atom is bound to two different carbon atoms, each of which is part of an organic radical; as, amyl ether; valeric ether; methyl ethyl ether.  The general formular for an ether is ROR´, in which R and R´ are organic radicals which may be of similar or different structure.  If R and R´ are different parts of the same organic radical, the structure forms a cyclic ether.
 Complex ether, Mixed ether Chem., an ether in which the ether oxygen is attached to two radicals having different structures; as, ethyl methyl ether, C2H5.O.CH3.
 Compound ether Chem., an ethereal salt or a salt of some hydrocarbon as the base; an ester.
 Ether engine Mach., a condensing engine like a steam engine, but operated by the vapor of ether instead of by steam.

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