The Collaborative International Dictionary of English v.0.48:

Detract \De*tract"\, v. i.
   To take away a part or something, especially from one's
   credit; to lessen reputation; to derogate; to defame; --
   often with from.
   [1913 Webster]

         It has been the fashion to detract both from the moral
         and literary character of Cicero.        --V. Knox.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Detract \De*tract"\, v. t. [imp. & p. p. Detracted; p. pr. &
   vb. n. Detracting.] [L. detractus, p. p. of detrahere to
   detract; de + trahere to draw: cf. F. d['e]tracter. See
   Trace.]
   1. To take away; to withdraw.
      [1913 Webster]

            Detract much from the view of the without. --Sir H.
                                                  Wotton.
      [1913 Webster]

   2. To take credit or reputation from; to defame.
      [1913 Webster]

            That calumnious critic . . .
            Detracting what laboriously we do.    --Drayton.

   Syn: To derogate; decry; disparage; depreciate; asperse;
        vilify; defame; traduce. See Decry.
        [1913 Webster]

WordNet (r) 3.0 (2006):

detract
    v 1: take away a part from; diminish; "His bad manners detract
         from his good character" [syn: take away, detract]