/ Thesaurus / N Synonyms of newton's third law of motion Find synonyms for: Noun1. third law of motion, Newton's third law of motion, Newton's third law, law of action and reaction, Newton's law of motion, Newton's law, law of motionusage: action and reaction are equal and oppositeWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: reticent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language