/ Dictionary / Index M mpg: Meaning and Definition of Find definitions for: mpg Pronunciation: [key] miles per gallon. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. MPers mph Related Content Daily Word Quiz: reiterate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language