The Collaborative International Dictionary of English v.0.48:

Calumniate \Ca*lum"ni*ate\, v. i.
   To propagate evil reports with a design to injure the
   reputation of another; to make purposely false charges of
   some offense or crime.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Calumniate \Ca*lum"ni*ate\, v. i. [imp. & p. p. Calumniated;
   p. pr. & vb. n. calumniating.] [L. calumniatus, p. p. of
   calumniari. See Calumny, and cf. Challenge, v. t.]
   To accuse falsely and maliciously of a crime or offense, or
   of something disreputable; to slander; to libel.
   [1913 Webster]

         Hatred unto the truth did always falsely report and
         calumniate all godly men's doings.       --Strype.
   [1913 Webster]

   Syn. -- To asperse; slander; defame; vilify; traduce;
      belie; bespatter; blacken; libel. See Asperse.
      [1913 Webster]

WordNet (r) 3.0 (2006):

calumniate
    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]