/ Dictionary / Index I ill-founded: Meaning and Definition of Find definitions for: ill-found•ed Pronunciation: (il'foun'did), [key] — adj. based on weak evidence, illogical reasoning, or the like: an ill-founded theory. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ill-formed ill-gotten 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