: not valid: such as
a
: having no force or effect
The judge declared that the contract was invalid.
b
: not based on truth or fact : not logical or correct
an invalid argument
plural invalids
: a person who needs to be cared for because of injury or illness
Her husband has become an invalid.
—often used before another nounShe cares for her invalid husband at home.
invalids; invalided; invaliding
British
: to release (someone) from active military service because of illness or injury
—usually used as (be) invalided
He was invalided out of the army.
He was invalided home.
Cite this Entry
“Invalid.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/invalid. Accessed 23 Jul. 2026.
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