Source : Webster's Revised Unabridged Dictionary (1913)

Appreciation \Ap*pre`ci*a"tion\, n. [Cf. F. appr['e]ciation.]
   1. A just valuation or estimate of merit, worth, weight,
      etc.; recognition of excellence.

   2. Accurate perception; true estimation; as, an appreciation
      of the difficulties before us; an appreciation of colors.

            His foreboding showed his appreciation of Henry's
            character.                            --J. R. Green.

   3. A rise in value; -- opposed to {depreciation}.

Source : WordNet®

appreciation
     n 1: understanding of the nature or meaning or quality or
          magnitude of something; "he has a good grasp of
          accounting practices" [syn: {grasp}, {hold}]
     2: delicate discrimination (especially of aesthetic values);
        "arrogance and lack of taste contributed to his rapid
        success"; "to ask at that particular time was the ultimate
        in bad taste" [syn: {taste}, {discernment}, {perceptiveness}]
     3: an expression of gratitude; "he expressed his appreciation
        in a short note"
     4: a favorable judgment; "a small token in admiration of your
        works" [syn: {admiration}]
     5: an increase in price or value; "an appreciation of 30% in
        the value of real estate" [ant: {depreciation}]