disculpate

from The Collaborative International Dictionary of English v.0.48

Disculpate \Dis*cul"pate\, v. t. [imp. & p. p. {Disculpated}; p.
   pr. & vb. n. {Disculpating}.] [LL. disculpatus, p. p. of
   disculpare to disculpate; dis- + L. culpare to blame, culpa
   fault.]
   To free from blame or the imputation of a fault; to
   exculpate.
   [1913 Webster]

         I almost fear you think I begged it, but I can
         disculpate myself.                       --Walpole.
   [1913 Webster]