| verb | declare invalid “The contract was annulled” |
| verb | make invalid for use “cancel cheques or tickets” |
| verb | show to be invalid |
| verb | take away the legal force of or render ineffective “invalidate a contract” |
| invalidation | noun | (law) a formal termination (of a relationship or a judicial proceeding etc) |
| invalidator | noun | an official who can invalidate or nullify |
| annulment | noun | (law) a formal termination (of a relationship or a judicial proceeding etc) |
| voidable | adjective | capable of being rescinded or voided |
| void | noun | the state of nonexistence |
| voider | noun | an official who can invalidate or nullify |
| nullifier | noun | an official who can invalidate or nullify |
| nullification | noun | the states'-rights doctrine that a state can refuse to recognize or to enforce a federal law passed by the United States Congress |
| vitiation | noun | nullification by the destruction of the legal force; rendering null |