The Collaborative International Dictionary of English v.0.48:

Asperse \As*perse"\, v. t. [imp. & p. p. Aspersed; p. pr. &
   vb. n. Aspersing.] [L. aspersus, p. p. of aspergere to
   scatter, sprinkle; ad + spargere to strew. See Sparse.]
   1. To sprinkle, as water or dust, upon anybody or anything,
      or to besprinkle any one with a liquid or with dust.
      --Heywood.
      [1913 Webster]

   2. To bespatter with foul reports or false and injurious
      charges; to tarnish in point of reputation or good name;
      to slander or calumniate; as, to asperse a poet or his
      writings; to asperse a man's character.
      [1913 Webster]

            With blackest crimes aspersed.        --Cowper.
      [1913 Webster]

   Syn: To slander; defame; detract from; calumniate; vilify.

   Usage: To Asperse, Defame, Slander, Calumniate. These
          words have in common the idea of falsely assailing the
          character of another. To asperse is figuratively to
          cast upon a character hitherto unsullied the
          imputation of blemishes or faults which render it
          offensive or loathsome. To defame is to detract from a
          man's honor and reputation by charges calculated to
          load him with infamy. Slander (etymologically the same
          as scandal) and calumniate, from the Latin, have in
          common the sense of circulating reports to a man's
          injury from unworthy or malicious motives. Men asperse
          their neighbors by malignant insinuations; they defame
          by advancing charges to blacken or sully their fair
          fame; they slander or calumniate by spreading
          injurious reports which are false, or by magnifying
          slight faults into serious errors or crimes.
          [1913 Webster]

WordNet (r) 3.0 (2006):

asperse
    v 1: charge falsely or with malicious intent; attack the good
         name and reputation of someone; "The journalists have
         defamed me!" "The article in the paper sullied my
         reputation" [syn: defame, slander, smirch, asperse,
         denigrate, calumniate, smear, sully, besmirch]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "asperse":
   affront, calumniate, christen, defame, denigrate, deride, immerse,
   insult, libel, mock, offend, scandal, scandalize, slander, slur,
   sprinkle, taunt, traduce



The Devil's Dictionary (1881-1906):

ASPERSE, v.t.  Maliciously to ascribe to another vicious actions which
one has not had the temptation and opportunity to commit.