New ‧ ton, Sir Isaac /ˈnjuːtn $ ˈnuː-/ BrE AmE
(1642–1727) a British ↑ physicist and ↑ mathematician who is best known for discovering ↑ gravity (=the force that causes things to fall towards the ground or to be pulled towards stars or ↑ planet s in space). He made many other important scientific discoveries, and is considered to be one of the most important scientists who ever lived. Until the early 20th century, modern ↑ physics was based on Newton's work, and it is sometimes called Newtonian physics. He is often shown in pictures holding an apple, because there is a story that he discovered the law of gravity when an apple fell on his head while he was sitting under a tree.