The state of being invalid; lack of validity.(noun)
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Use "invalidity" in a sentence
"Thirdly, claiming invalidity is not as easy as the Conservatives would have us believe, and implies that the medical profession are just giving sick notes away, willy-nilly."
"He recommended that Marshoff obtain legal advice about ways to rectify the "invalidity" of her decision in the absence of the committee's advice."
"A rare "invalidity" this -- a little confusing easy classifications."