Source : Webster's Revised Unabridged Dictionary (1913)

Besmirch \Be*smirch"\, v. t. [imp. & p. p. {Besmirched}; p. pr.
   & vb. n. {Besmirching}.]
   To smirch or soil; to discolor; to obscure. Hence: To
   dishonor; to sully. --Shak.

Source : WordNet®

besmirch
     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}]
     2: smear so as to make dirty or stained [syn: {smirch}]