Source : Webster's Revised Unabridged Dictionary (1913)

Ratio \Ra"ti*o\, n. [L., fr. reri, ratus, to reckon, believe,
   think, judge. See {Reason}.]
   1. (Math.) The relation which one quantity or magnitude has
      to another of the same kind. It is expressed by the
      quotient of the division of the first by the second; thus,
      the ratio of 3 to 6 is expressed by 3/6 or 1/2; of a to b
      by a/b; or (less commonly) the second is made the
      dividend; as, a:b = b/a.

   Note: Some writers consider ratio as the quotient itself,
         making ratio equivalent to a number. The term ratio is
         also sometimes applied to the difference of two
         quantities as well as to their quotient, in which case
         the former is called arithmetical ratio, the latter,
         geometrical ratio. The name ratio is sometimes given to
         the rule of three in arithmetic. See under {Rule}.

   2. Hence, fixed relation of number, quantity, or degree;
      rate; proportion; as, the ratio of representation in
      Congress.

   {Compound ratio}, {Duplicate ratio}, {Inverse ratio}, etc.
      See under {Compound}, {Duplicate}, etc.

   {Ratio of a geometrical progression}, the constant quantity
      by which each term is multiplied to produce the succeeding
      one.

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.

         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.