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.
   [1913 Webster]

         Compound substances are made up of two or more simple
         substances.                              --I. Watts.
   [1913 Webster]

   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.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Subtraction \Sub*trac"tion\, n. [L. subtractio a drawing back.
   See Subtract, and cf. Substraction.]
   1. The act or operation of subtracting or taking away a part.
      [1913 Webster]

   2. (Math.) The taking of a lesser number or quantity from a
      greater of the same kind or denomination; an operation for
      finding the difference between two numbers or quantities.
      [1913 Webster]

   3. (Law) The withdrawing or withholding from a person of some
      right to which he is entitled by law.
      [1913 Webster]

   Note: Thus the subtraction of conjugal rights is when either
         the husband or wife withdraws from the other and lives
         separate without sufficient reason. The subtraction of
         a legacy is the withholding or detailing of it from the
         legatee by the executor. In like manner, the
         withholding of any service, rent, duty, or custom, is a
         subtraction, for which the law gives a remedy.
         --Blackstone.
         [1913 Webster]

WordNet (r) 3.0 (2006):

subtraction
    n 1: an arithmetic operation in which the difference between two
         numbers is calculated; "the subtraction of three from four
         leaves one"; "four minus three equals one" [syn:
         subtraction, minus]
    2: the act of subtracting (removing a part from the whole); "he
       complained about the subtraction of money from their
       paychecks" [syn: subtraction, deduction] [ant:
       addition]

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "subtraction":
   abatement, abridgment, absence, abstraction, addition, alienation,
   alleviation, approximation, attenuation, awayness, blank,
   contraction, dampening, damping, decrease, decrement, decrescence,
   deduction, deflation, depreciation, depression, deprivation,
   detachment, differentiation, diminishment, diminution,
   disarticulation, disassociation, disconnectedness, disconnection,
   discontinuity, discount, disengagement, disjointing, disjunction,
   dislocation, disunion, division, divorce, divorcement, dying,
   dying off, equation, evolution, extenuation, extrapolation,
   fade-out, incoherence, integration, interpolation, inversion,
   involution, isolation, lack, languishment, lessening, letup,
   lowering, luxation, miniaturization, mitigation, multiplication,
   neverness, nonexistence, nonoccurrence, nonpresence, notation,
   nowhereness, parting, partition, practice, proportion, rebate,
   reduction, relaxation, removal, sagging, scaling down,
   segmentation, separation, separatism, simplicity, subdivision,
   transformation, want, weakening, withdrawal, zoning



Bouvier's Law Dictionary, Revised 6th Ed (1856):

SUBTRACTION. The act of withholding or detaining anything unlawfully.