a wheel for transmitting power and motion between a driving and a driven part, either by friction or by means of teeth.
Origin of idle wheel
First recorded in 1795–1805
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a gearwheel interposed between two others to transmit torque without changing the direction of rotation to the velocity ratioAlso called: idler
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012