1. invalidate, annul, quash, void, avoid, nullify -- (declare invalid; "The contract was annulled"; "void a plea")
2. revoke, annul, lift, countermand, reverse, repeal, overturn, rescind, vacate -- (cancel officially; "He revoked the ban on smoking"; "lift an embargo"; "vacate a death sentence")
1.
But never mind, glory to the mattress which annuls a cannon. - from Les Miserables by Victor Hugo