1. invalidate, annul, quash, void, avoid, nullify -- (declare invalid; "The contract was annulled"; "void a plea")
2. cancel, invalidate -- (make invalid for use; "cancel cheques or tickets")
3. invalidate, nullify -- (show to be invalid)
4. invalidate, void, vitiate -- (take away the legal force of or render ineffective; "invalidate a contract")
1.
Nevertheless, there was always a great deal of mystery about these leaders, and no certain fact can invalidate the singular arrogance of this reply made later on by a man accused before the Court of Peers-. - from Les Miserables by Victor Hugo