/ Dictionary / Index M Mach's principle: Meaning and Definition of Find definitions for: Mach's' prin"ciple Pronunciation: [key] the proposition that there is no absolute space and that the inertia and acceleration of a body are determined by all of the matter of the universe. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Mach scale Machu Picchu Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language