(in automotive vehicles) a belt, driven by the crankshaft of an engine, that turns a fan for drawing cooling air through the radiator.
Baseball Slang True Fans Should KnowThe game dates back a long way (the first pro team started in 1869—the Cincinnati Reds) so there’s a long history here.
Origin of fan belt
First recorded in 1920–25
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for fan belt
any belt that drives a fan, esp the belt that drives a cooling fan together with a dynamo or alternator in a car engine
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