seat belt

Safety device in a motor vehicle or aeroplane that is designed to reduce the risk of injury to a passenger from sudden changes in velocity, such as during a collision or when brakes are applied sharply. In an emergency, it extends the time over which the decelerating force acts on a passenger thereby reducing that force to a safe level. It also spreads the force over a broad band across the chest and over the hip bone, reducing the pressure applied to the person.