The Collaborative International Dictionary of English v.0.48:

Disavow \Dis`a*vow"\, v. t. [imp. & p. p. Disavowed; p. pr. &
   vb. n. Disavowing.] [F. d['e]savouer; pref. d['e]s- (L.
   dis-) + avouer to avow. See Avow, and cf. Disavouch.]
   1. To refuse strongly and solemnly to own or acknowledge; to
      deny responsibility for, approbation of, and the like; to
      disclaim; to disown; as, he was charged with embezzlement,
      but he disavows the crime.
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            A solemn promise made and disavowed.  --Dryden.
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   2. To deny; to show the contrary of; to disprove.
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            Yet can they never
            Toss into air the freedom of my birth,
            Or disavow my blood Plantagenet's.    --Ford.
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