/ Dictionary / Index N NMN: Meaning and Definition of Find definitions for: NMN Pronunciation: [key] no middle name. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. NMI NMR Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language