If you're not familiar with the term "southpaw," trying to conjure its meaning might send your imagination all over the place. The term actually refers to people who are left-handed, and it has been part and parcel of describing the trait since the 1800s.
Turns out, we have baseball and boxing to thank for associating southpaw with left-handedness. Perhaps the earliest recorded usage of the word "southpaw" appears in an 1813 letter to the editor in The Tickler, a satirical Philadelphia-based newspaper, but it soon became inexorably linked with boxing — although there are differing opinions as to its origins.
An 1848 political cartoon illustrates the use of "southpaw" as a term for someone striking a blow with their left hand, in this case a Democratic contender for president, Lewis Cass, uses a southpaw haymaker to knock out both his rival — Zachary Taylor — and Taylor's running mate, Millard Filmore. It is Filmore's caricature, resplendent with a black eye, who said, "Curse the old hoss wot a south paw he has given me!"
The association with boxing becomes even stronger as the 1800s progress. An 1860 prize-fight in which two boxing opponents have a bare-knuckled battle, is summed up in a New York Herald report that David Woods, who is left-handed, in the ninth round "planted his 'south paw' under [his opponent's] chin, laying him out flat as a pancake."
The term "southpaw" has early origins in baseball too, where it referred to any left-handed player, but especially a left-handed pitcher. There are claims that the term arose from the way ballparks in the 1800s were built — with home plate to the west, which meant that a left-handed player facing west would be pitching with his "south" paw.
However, there are several other accounts of the term "southpaw" being used to describe not only pitchers, but any player; an 1875 edition of a St. Louis newspaper that referred to a left-handed batter as a southpaw, a left-handed first baseman described as a southpaw in an 1858 edition of the New York Atlas, and so on.
And there's the issue of orientation. Not all big league stadiums faced the west. It's likely, though, that at Chicago's West Side Park, which did have a home plate that faced west, sports writers popularized the term.
Major League Baseball's official historian, John Thorn, has chronicled the term's move from boxing to baseball, and believes the terms "south" and "left" have both been associated with devilish forces, which would make a southpaw stance the starting point for a wicked throw.