a pitcher brought into a game to replace another pitcher, often in a critical situation.
a pitcher regularly so used, as opposed to one who regularly starts games.
Origin of relief pitcher
First recorded in 1945–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for relief pitcher
baseball a pitcher who replaces a side's main pitcher during a gameAlso called: reliever
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