Definition of: pulley

(pl′ē) noun
1. A wheel grooved to receive a rope, and usually mounted in a block, used to increase the mechanical advantage of an applied force and to transmit or change the direction of power by means of a flexible belt or rope; a sheave.
2. A block with its pulleys or tackle.
3. Mech. A flat or flanged wheel driving, carrying, or being driven by a flat belt, used in a system for transmitting power. [<OF polie <Med. L poleia, prob. ult <Gk. polos a pivot, axis]
PULLEYS
a. Single fixed.
b. Single runner.
c. Fixed and runner.
d. First system.
e. Second system.