invalidin·val·id /ɪnˈvælɪd/ adjectiveadj1LAW an invalid contract, agreement, document etc is not legally or officially acceptableWellcome’s patent to the drug wasruled invalid because the company didn’t invent the compound.
evidence obtained using invalid warrants
2not based on true facts and therefore not rightThe promotions lacked balance and madeinvalid comparisons between rival products.
3COMPUTING if something that you type into a computer is invalid, the computer does not recognize or accept itThe date is in an invalid format.
—invalidity noun [uncountableU]The bonds are perforated with small holes to show their invalidity.