/ Dictionary / Index M monoammonium phosphate: Meaning and Definition of Find definitions for: mon'o•am•mo'ni•um phos'phate Pronunciation: (mon'ō-u-mō'nē-um, mon"-), [key] — Chem. Chem. a white, crystalline, moderately water-soluble compound, NHHPO, used as fertilizer, in fire extinguishers, etc. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. monoamine oxidase inhibitor monoatomic Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language