From Longman Dictionary of Contemporary Englishsouthpawsouth‧paw /ˈsaʊθpɔː $ -pɒː/ noun [countable] informal DSsomeone who uses their left hand more than their right hand, especially a pitcher in baseball or a boxer
Examples from the Corpus
southpaw• Almost certainly the right forefinger, unless Gerry Boden happened to be a southpaw.• Penalosa's lack of mobility is counter-balanced by his southpaw stance and hard punch. 