Green’s Dictionary of Slang

1. a person who has lost one or both their limbs on their right side (arm and leg).

1918		‘A-No. 1’ Mother of the Hoboes 43: The Rating Of The Tramps. 18 Righty: train rider who lost right arm and leg.
1923		N. Anderson Hobo 100: [From A No. 1, The Famous Tramp] 18. Righty. Train rider who lost right arm and leg.
1949		Monteleone Criminal Sl. (rev. edn) 194: righty A person who has lost a right arm or leg.

2. right-handedness.

1942

N. Algren Never Come Morning (1988) 106: Sometimes his left hand would go so numb he couldn’t close it to pitch pennies with and had to change to rightie.

3. a right-hander; also used adv.

1949		Sun (Baltimore) 3 June 18/7: Pie—a rightie [...] compiled an all-time average of 300-plus against all kinds of pitching.
1958		Mad mag. Jan.–Feb. 6: You have the President’s gold clubs as left-handed models. Don’t you realize Eisenhower is a rightie!?!
1963		R.I. McDavid Mencken’s Amer. Lang. 564: In baseball, switch hitters speak of their relative prowess batting lefty and righty.
1975		New Yorker 15 Sept. 27/3: The Sox put in [...] Cleveland, a righty who hadn’t seen action in sixteen days.
2000		F.X. Toole Rope Burns 49: You’re saying you, as a rightie, are going out there to outjab a southpaw?, now, come on.
2012		J.J. DeCeglie ‘Death Cannot Be Delegated’ in Crime Factory: Hard Labour [ebook] I knew he was a righty so I shoved the gun to that temple [...] so as the police ate the suicide.

4. a right-winger.

2011

Guardian CIF 8 Aug. 🌐 The people who have been commenting on the riots are righties dressed up as lefties.