• make or prove (an argument, statement, or theory) unsound or erroneous

Synonyms: disprove, show/prove to be false, refute, explode, contradict, rebut, negate, gainsay, belie, give the lie to, discredit, expose, debunk, knock the bottom out of, drive a coach and horses through

• deprive (an official document or procedure) of legal validity because it contravenes a regulation or law

Synonyms: render invalid, void, nullify, annul, negate, cancel, quash, veto, overturn, overrule, override, undo, reverse