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.
A solemn promise made and disavowed. --Dryden.
2. To deny; to show the contrary of; to disprove.
Yet can they never
Toss into air the freedom of my birth,
Or disavow my blood Plantagenet's. --Ford.