first law of motion n a body remains at rest or in motion with a constant velocity unless acted upon by an external force Synonym(s) Newton's first law of motion Newton's first law
News & Articles first law of motion Laif Meidell: Vietnam stocks way up; Russia, China take hits To paraphrase Newton's First Law of Motion, a body in motion will stay in motion until acted upon by and outside force. March 13, 2014 - Reno Gazette-Journal