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" ;