/ Dictionary / Index I invalidism: Meaning and Definition of Find definitions for: in•va•lid•ism Pronunciation: (in'vu-li-diz"um), [key] — n. prolonged ill health. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: invalidism (Thesaurus) invalidate invalidity 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