adjective , noun , verb
■ adjective / ɪnˈvælɪd; NAmE /
1.
not legally or officially acceptable :
The treaty was declared invalid because it had not been ratified.
People with invalid papers are deported to another country.
2.
not based on all the facts, and therefore not correct :
an invalid argument
3.
( computing ) of a type that the computer cannot recognize :
An error code will be displayed if any invalid information has been entered.
invalid characters
OPP valid
■ noun
/ ˈɪnvəlɪd; BrE also ˈɪnvəliːd/ a person who needs other people to take care of them, because of illness that they have had for a long time :
She had been a delicate child and her parents had treated her as an invalid.
his invalid wife
■ verb
/ˈɪnvəlɪd; ˈɪnvəliːd/ [ vn ] invalid sb (out) | invalid sb (out of sth) ( BrE ) to force sb to leave the armed forces because of an illness or injury :
He was invalided out of the army in 1943.
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WORD ORIGIN
noun and verb mid 17th cent. (as an adjective in the sense infirm or disabled ): a special sense of invalid (adjective), with a change of pronunciation.
adjective mid 16th cent. (earlier than valid ): from Latin invalidus , from in- not + validus strong (from valere be strong).