/ Dictionary / Index M megajoule: Meaning and Definition of Find definitions for: meg•a•joule Pronunciation: (meg'u-joul", -jl"), [key] — n. Physics. a unit of work or energy, equal to one million joules. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. megahit megakaryoblast 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