Pronunciation: (pool'ē), [key]
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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.