/ Dictionary / Index I ideatum: Meaning and Definition of Find definitions for: i•de•a•tum Pronunciation: (ī"dē-ā'tum, ē"dē-), [key] — pl. -ta (in epistemology) the object of knowledge as known by the mind. Cf. datum (def. 3). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ideational idée fixe* Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language