/ Dictionary / Index I invalidity: Meaning and Definition of Find definitions for: in•va•lid•i•ty Pronunciation: (in"vu-lid'i-tē), [key] — n. lack of validity. in•va•lid•i•ty Pronunciation: (in"vu-lid'i-tē), [key] — n. invalidism. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: invalidity (Thesaurus) invalidism invaluable Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language