A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a cable or belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power. In nautical contexts, the assembly of wheel, axle, and supporting shell is referred to as a "block."
- Oxford English Dictionary.Oxford University Press, 1989. Quote = A wheel with a groove round its rim, a sheave. A wheel or drum fixed on a shaft and turned by a belt, cable, etc.,