Source : Webster's Revised Unabridged Dictionary (1913)

Reduce \Re*duce"\ (r[-e]*d[=u]s"), v. t. [imp. & p. p. {Reduced}
   (-d[=u]st"),; p. pr. & vb. n. {Reducing} (-d[=u]"s[i^]ng).]
   [L. reducere, reductum; pref. red-. re-, re- + ducere to
   lead. See {Duke}, and cf. {Redoubt}, n.]
   1. To bring or lead back to any former place or condition.
      [Obs.]

            And to his brother's house reduced his wife.
                                                  --Chapman.

            The sheep must of necessity be scattered, unless the
            great Shephered of souls oppose, or some of his
            delegates reduce and direct us.       --Evelyn.

   2. To bring to any inferior state, with respect to rank,
      size, quantity, quality, value, etc.; to diminish; to
      lower; to degrade; to impair; as, to reduce a sergeant to
      the ranks; to reduce a drawing; to reduce expenses; to
      reduce the intensity of heat. ``An ancient but reduced
      family.'' --Sir W. Scott.

            Nothing so excellent but a man may fasten upon
            something belonging to it, to reduce it.
                                                  --Tillotson.

            Having reduced Their foe to misery beneath their
            fears.                                --Milton.

            Hester Prynne was shocked at the condition to which
            she found the clergyman reduced.      --Hawthorne.

   3. To bring to terms; to humble; to conquer; to subdue; to
      capture; as, to reduce a province or a fort.

Reducing \Re*du"cing\ (r?*d?"s?ng),
   a & n. from {Reduce}.

   {Reducing furnace} (Metal.), a furnace for reducing ores.

   {Reducing pipe fitting}, a pipe fitting, as a coupling, an
      elbow, a tee, etc., for connecting a large pipe with a
      smaller one.

   {Reducing valve}, a device for automatically maintaining a
      diminished pressure of steam, air, gas, etc., in a pipe,
      or other receiver, which is fed from a boiler or pipe in
      which the pressure is higher than is desired in the
      receiver.

Source : WordNet®

reducing
     n 1: any process in which electrons are added to an atom or ion
          (as by removing oxygen or adding hydrogen); always
          occurs accompanied by oxidation of the reducing agent
          [syn: {reduction}]
     2: loss of excess weight (as by dieting); becoming slimmer; "a
        doctor supervised her reducing"