/ Dictionary / Index M mononuclear: Meaning and Definition of Find definitions for: mon•o•nu•cle•ar Pronunciation: (mon"u-n'klē-ur, -ny'- or, by metathesis, -kyu-lur), [key] — adj. having only one nucleus. (of hydrocarbons) monocyclic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mononuclear (Thesaurus) Monongahela mononucleosis Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language