Revocation is the official act of taking a law, a decision, or an agreement back, so that it no longer has force. A court, a government, or a school can announce a revocation: of a licence, a visa, a privilege, a part of a contract. It is a noun for paperwork and power, not for changing your mind about a restaurant. Though actually the verb people know first is revoke; revocation is the name of that act, and it sounds legal. The old Latin picture is “a calling back”: the rule is called back, as if it were a person told to return.