The Collaborative International Dictionary of English v.0.48:

Derogation \Der`o*ga"tion\, n. [L. derogatio: cf. F.
   d['e]rogation.]
   1. The act of derogating, partly repealing, or lessening in
      value; disparagement; detraction; depreciation; --
      followed by of, from, or to.
      [1913 Webster]

            I hope it is no derogation to the Christian
            religion.                             --Locke.
      [1913 Webster]

            He counted it no derogation of his manhood to be
            seen to weep.                         --F. W.
                                                  Robertson.
      [1913 Webster]

   2. (Stock Exch.) An alteration of, or subtraction from, a
      contract for a sale of stocks.
      [1913 Webster]

WordNet (r) 3.0 (2006):

derogation
    n 1: a communication that belittles somebody or something [syn:
         disparagement, depreciation, derogation]
    2: (law) the partial taking away of the effectiveness of a law;
       a partial repeal or abolition of a law; "any derogation of
       the common law is to be strictly construed"