/ Dictionary / Index I imaginary unit: Meaning and Definition of Find definitions for: imag'inary u'nit Pronunciation: [key] — Math. Math. the complex number i. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. imaginary part imagination 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