Green’s Dictionary of Slang

1. a left-hander, esp. in boxing.

[1867		Knights Templar (Michigan) Proceedings 75: We of New Jersey don’t want to have our ‘destitute widows’ and ‘helpless orphans’ defended by a valiant Knight who wields his sword in his ‘southpaw’].
1868		Buffalo Morn. Exp. (NY) 17 June 4/4: The way ‘Southpaw’ Joe [...] can swing the ashew [...] is a caution to pitchers.
1871		Appleton’s Journal (N.Y.) 16 Dec. 692/2: Why is the right hand the andiest? Is it so from instinct or education? for, anti-dexters and ‘south-paws,’ or left-handed persons, are rare exceptions to the rule.
1888		World (N.Y.) 16 Sept. 3/3: [subhead] ‘South-paw’ Morris Proves A Mystery To The Giants.
1892		DN I 227: The president spoke of south meaning ‘left’ in southpaw, a left-handed base-ball pitcher; south-handed had been mentioned to him by Englishmen .
1903		Wash. Times (DC) 30 Jan. 5/3: A novel contest took place on the Palace alleys last night, when the Northpaws and the Southpaws met. The teams are made up of some of the best bowlers in the city.
1912		Van Loan ‘Ten-Thousand-Dollar Arm’ in Ten-Thousand-Dollar Arm 2: Bruno Smelzer was a left-hander. Check over the list of the great southpaws of the past.
1922		Bismarck Trib. (ND) 3 Aug. 6/3: Left-handed pitchers [...] are much sought after [...] Since the southpaws are greatly in the minority [...].
1936		Charleston (WV) Daily Mail 9 Oct. 8/8: The man with the score-card calls a left-handed pitcher ‘a south-paw,’ but the ball players themselves would more than likely call him ‘cockeyed,’ ‘twirly thumbs’ or ‘corkscrew.’.
1942		N. Algren Never Come Morning (1988) 11: Bruno Lefty Bicek, ace southpaw of the 26th Ward Warriors.
1952		(con. 1920s) G. Fowler Schnozzola 41: Marat said that his horse definitely was not left-handed. Durante insisted that it was [...] ‘Mr. Marat,’ said Jimmy, ‘I’ll prove to you that your horse is a southpaw.’.
1967		P. Thomas Down These Mean Streets (1970) 260: I pushed him away and he almost tore my jaw off with a left cross. I hadn’t figured him for a southpaw.
1977		P. Hamill Flesh and Blood (1978) 46: There weren’t too many southpaws in jail.
1986		M.W. Brown N.Y. Times 25 Apr. n.p.: Is God a semiambidextrous southpaw? [R].
1997–2000		Da Bomb 🌐 26: Southpaw: Left handed pitcher.
2006		F.X. Toole Pound for Pound 74: [...] being a hard-hitting southpaw wasn’t enough.

2. the left hand.

1885		N.Y. Sporting Life 14 Jan. 4: Morris’ quick throw over to first with that south paw of his.
1902		‘Hugh McHugh’ It’s Up to You 28: When can I grab you by the southpaw and lead you off to a minister’s.
1912		Van Loan ‘Ten-Thousand-Dollar Arm’ in Ten-Thousand-Dollar Arm 28: The fans [...] did not like to see him gambling his venerable southpaw against a pennant.
1948		Chicago Trib. 20 Apr. I 20/5: He waved his big southpaw and ducked under the roof [DA].
1972		J. Hibberd A Stretch of the Imagination (2000) 138: I took him by the southpaw.

3. a blow with the left hand.

1925

T.A. Dorgan in Zwilling TAD Lex. (1993) 30: An de ole soufpaw to de darby kelly He don’t like ’em down dere.