[poo
l-ee] 
| 1. | a wheel, with a grooved rim for carrying a line, that turns in a frame or block and serves to change the direction of or to transmit force, as when one end of the line is pulled to raise a weight at the other end: one of the simple machines. |
| 2. | a combination of such wheels in a block, or of such wheels or blocks in a tackle, to increase the force applied. |
| 3. | a wheel driven by or driving a belt or the like, used to deliver force to a machine, another belt, etc., at a certain speed and torque. |
| pul·ley (pŏŏl'ē) n. pl. pul·leys
[Middle English poley, from Old French polie and from Medieval Latin poliva, both ultimately from Greek polos, axis; see kwel-1 in Indo-European roots.] |
pulley (p l'ē) Pronunciation Key
A machine consisting of a wheel over which a pulled rope or chain runs to change the direction of the pull used for lifting a load. Combinations of two or more pulleys working together reduce the force needed to lift a load. See also block and tackle. |