Pulley

[poo l-ee] /ˈpʊl i/

noun, plural pulleys.
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.
/ˈpʊlɪ/
noun
1.
a wheel with a grooved rim in which a rope, chain, or belt can run in order to change the direction or point of application of a force applied to the rope, etc
2.
a number of such wheels pivoted in parallel in a block, used to raise heavy loads
3.
a wheel with a flat, convex, or grooved rim mounted on a shaft and driven by or driving a belt passing around it
n.

late 13c., from Old French polie, pulie “pulley, windlass” (12c.) and directly from Medieval Latin poliva, puliva, probably from Medieval Greek *polidia, plural of *polidion “little pivot,” diminutive of Greek polos “pivot, axis” (see pole (n.2)). As a verb from 1590s.
pulley
(pl’ē)
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.