1. to reject as having no authority or binding force: to repudiate a claim.
2. to cast off or disown: to repudiate a son.
3. to reject with disapproval or condemnation: to repudiate a new doctrine.
4. to reject with denial: to repudiate a charge as untrue.
5. to refuse to acknowledge and pay (a debt), as a state, municipality, etc.
http://dictionary.reference.com/browse/repudiate
Though he repudiated the claim that he had cheated on his essay, his professor still gave him a zero as he had no proof to back his claim of honesty.
