Source : Webster's Revised Unabridged Dictionary (1913)

Improvement \Im*prove"ment\, n.
   1. The act of improving; advancement or growth; promotion in
      desirable qualities; progress toward what is better;
      melioration; as, the improvement of the mind, of land,
      roads, etc.

            I look upon your city as the best place of
            improvement.                          --South.

            Exercise is the chief source of improvement in all
            our faculties.                        --Blair.

   2. The act of making profitable use or applicaton of
      anything, or the state of being profitably employed; a
      turning to good account; practical application, as of a
      doctrine, principle, or theory, stated in a discourse. ``A
      good improvement of his reason.'' --S. Clarke.

            I shall make some improvement of this doctrine.
                                                  --Tillotson.

   3. The state of being improved; betterment; advance; also,
      that which is improved; as, the new edition is an
      improvement on the old.

            The parts of Sinon, Camilla, and some few others,
            are improvements on the Greek poet.   --Addison.

   4. Increase; growth; progress; advance.

            There is a design of publishing the history of
            architecture, with its several improvements and
            decays.                               --Addison.

            Those vices which more particularly receive
            improvement by prosperity.            --South.

   5. pl. Valuable additions or betterments, as buildings,
      clearings, drains, fences, etc., on premises.

   6. (Patent Laws) A useful addition to, or modification of, a
      machine, manufacture, or composition. --Kent.

Source : WordNet®

improvement
     n 1: the act of improving something; "their improvements
          increased the value of the property"
     2: a change for the better; progress in development [syn: {betterment},
         {advance}]
     3: a condition superior to an earlier condition; "the new
        school represents a great improvement" [syn: {melioration}]
        [ant: {decline}]