Source : Webster's Revised Unabridged Dictionary (1913)

Reduction \Re*duc"tion\ (r?*d?k"sh?n), n. [F. r['e]duction, L.
   reductio. See {Reduce}.]
   1. The act of reducing, or state of being reduced; conversion
      to a given state or condition; diminution; conquest; as,
      the reduction of a body to powder; the reduction of things
      to order; the reduction of the expenses of government; the
      reduction of a rebellious province.

   2. (Arith. & Alq.) The act or process of reducing. See
      {Reduce}, v. t., 6. and {To reduce an equation}, {To
      reduce an expression}, under {Reduce}, v. t.

   3. (Astron.)
      (a) The correction of observations for known errors of
          instruments, etc.
      (b) The preparation of the facts and measurements of
          observations in order to deduce a general result.

   4. The process of making a copy of something, as a figure,
      design, or draught, on a smaller scale, preserving the
      proper proportions. --Fairholt.

   5. (Logic) The bringing of a syllogism in one of the
      so-called imperfect modes into a mode in the first figure.

   6. (Chem. & Metal.) The act, process, or result of reducing;
      as, the reduction of iron from its ores; the reduction of
      aldehyde from alcohol.

   7. (Med.) The operation of restoring a dislocated or
      fractured part to its former place.

   {Reduction ascending} (Arith.), the operation of changing
      numbers of a lower into others of a higher denomination,
      as cents to dollars.

   {Reduction descending} (Arith.), the operation of changing
      numbers of a higher into others of a lower denomination,
      as dollars to cents.

   Syn: Diminution; decrease; abatement; curtailment;
        subjugation; conquest; subjection.