The Collaborative International Dictionary of English v.0.48:

Depreciation \De*pre`ci*a"tion\
   (d[-e]*pr[=e]`sh[i^]*[=a]"sh[u^]n), n. [Cf. F.
   d['e]pr['e]ciation.]
   1. The act of lessening, or seeking to lessen, price, value,
      or reputation.
      [1913 Webster]

   2. The falling of value; reduction of worth. --Burke.
      [1913 Webster]

   3. the state of being depreciated.
      [1913 Webster]

WordNet (r) 3.0 (2006):

depreciation
    n 1: a decrease in price or value; "depreciation of the dollar
         against the yen" [ant: appreciation]
    2: decrease in value of an asset due to obsolescence or use
       [syn: depreciation, wear and tear]
    3: a communication that belittles somebody or something [syn:
       disparagement, depreciation, derogation]