/ Dictionary / Index I ill-formed: Meaning and Definition of Find definitions for: ill-formed Pronunciation: (il'fôrmd'), [key] — adj. badly formed. not conforming to the rules of a given language; ungrammatical (opposed to well-formed). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: ill-formed (Thesaurus) ill-fitted ill-founded Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language