From Longman Dictionary of Contemporary Englishinvalidin‧val‧id1 /ɪnˈvælɪd/ ●○○ adjective 1 USE somethinga contract, ticket, claim etc that is invalid is not legally or officially acceptable OPP valid Without the right date stamped on it, your ticket will be invalid.2 WRONG/INCORRECTan argument, reason etc that is invalid is not based on true facts or clear ideas, and lacks good judgment OPP valid3 if something you type into a computer is invalid, the computer does not recognize or accept it Filename in invalid format.
Examples from the Corpusinvalid• Ackerman said the argument was invalid.• When the council sought to evict him for non-payment of the extra rent he pleaded in defence that the resolution was invalid.• Do not detach the coupon or your ticket will be invalid.• For this reason, you can readily identify them as valid or invalid.• But the vote has been declared invalid because fewer than half the parents took part in the ballot.• The survey attempted to answer critics who have dismissed international comparisons as invalid because of differences in cultural expectations about health care.• In one attack his invalid car was stolen and smashed.• When I was a child, there was a man who came to our chapel in an invalid chair.• Mrs H described the knock at the door that woke her and her invalid husband at seven o'clock.• This passport is invalid. Look at the expiry date.• I'm afraid your ticket is invalid on this route.• As it turns out, the fears that govern such organizations derive in large part from invalid or negative core beliefs.invalidin‧va‧lid2 /ˈɪnvəliːd, -lɪd $ -lɪd/ noun [countable] MIsomeone who cannot look after themselves because of illness, old age, or injury I resented being treated as an invalid. —invalid adjective [only before noun]
Examples from the Corpusinvalid• Crippled by an inmate, he faces the rest of his life as an invalid.• My father's an invalid, and needs constant care.• Barbara decided to move her invalid mother to Mississippi, so that she could look after her herself.• I pictured nocturnal gamblers crouching over their cards, sleepless lovers writing letters, nurses sitting by the beds of invalids.• His elder brother Edwin was next in succession to the baronetcy, but he was a total invalid.invalidin‧va‧lid3 verb → be invalided outFrom Longman Business Dictionaryinvalidin‧val‧id /ɪnˈvælɪd/ adjective1LAW 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 warrants2not 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 [uncountable]The bonds are perforated with small holes to show their invalidity.Origin invalid1 (1500-1600) Latin invalidus, from validus; → VALID invalid2 (1600-1700) French invalide, from Latin invalidus; → INVALID1