A southpaw is someone who is left-handed, especially in sports. The term is most common in baseball, where a left-handed pitcher is called a southpaw. You might hear an announcer say, “The manager is bringing in a southpaw to face the next batter.”

Most ballparks were built so batters faced east (to keep the afternoon sun out of their eyes). This meant a left-handed pitcher's throwing arm was on the south side of the diamond. Someone noticed this and started calling lefties southpaws, and the name stuck.

Today, people use southpaw for left-handed athletes in boxing, basketball, and other sports. Left-handed players sometimes have an advantage because most athletes practice against right-handed opponents. A southpaw boxer throws punches from angles that right-handed fighters aren't used to defending. A southpaw basketball player might dribble and shoot in ways that surprise defenders who mostly face righties.

The term is always informal and often admiring. Nobody calls themselves a southpaw when filling out forms, but a left-handed pitcher might wear the label with pride.