From Longman Dictionary of Contemporary Englishinvalidin‧val‧id1 /ɪnˈvælɪd/ ●○○ adjective 🔊 🔊 1USE 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.2WRONG/INCORRECTan argument, reason etc that is invalid is not based on true facts or clear ideas, and lacks good judgment opp valid3if something you type into a computer is invalid, the computer does not recognize or accept it 🔊 Filename in invalid format.
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 Corpus
invalid• 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 invalidmother to Mississippi, so that she could look after her herself.• I picturednocturnal gamblers crouching over their cards, sleeplesslovers writing letters, nurses sitting by the beds of invalids.• His elder brother Edwin was next in succession to the baronetcy, but he was a totalinvalid.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.