A pitcher who does not start the game WordNet 3.0 & Open English WordNet

In baseball and softball, a relief pitcher or reliever is a pitcher who pitches in the game after the starting pitcher has been removed because of fatigue, ineffectiveness, injury, or ejection, or for other strategic reasons, such as inclement weather delays or pinch hitter substitutions. Wikipedia

A baseball or softball position Wikipedia Disambiguation

Baseball or softball pitcher who relieves a previous pitcher Wikidata

A relief pitcher. Wiktionary

Pitcher. Wiktionary (translation)

A pitcher who enters the game after the starting pitcher or another relief pitcher is removed due to injury, ineffectiveness, ejection from the game or fatigue. Wiktionary

Baseball: replacement pitcher. Wiktionary (translation)