/ Dictionary / Index L law of action and reaction: Meaning and Definition of Find definitions for: law' of ac'tion and reac'tion Pronunciation: [key] — Physics. Physics. See under Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. lawn tennis law of areas Related Content Daily Word Quiz: lunar Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language