/ Dictionary / Index M M-16: Meaning and Definition of Find definitions for: M-16 Pronunciation: (em'siks"tēn'), [key] — pl. M-16s. a lightweight, fully automatic rifle shooting a small-caliber bullet at an extremely high velocity: a U.S. Army combat weapon for mobile units and jungle fighting. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. M-14 ma Related Content Daily Word Quiz: feline Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language