Green’s Dictionary of Slang

1. a person or project that is a potential success.

1900		Ade More Fables in Sl. (1960) 123: The Organization seemed to be a Winner.
1908		‘O. Henry’ ‘A Tempered Wind’ in Gentle Grafter (1915) 177: Conservative, homely, rough, shrewd, saving — that’s your pose. It’s a winner in New York.
1916		Funny Wonder 5 Feb. 1: Me, a winner every time.
1920		E. O’Neill Beyond the Horizon II ii: Gosh, I never saw a father so tied up in a kid as Rob is! [...] She’s surely a little winner.
1936		J. Curtis Gilt Kid 93: Listen, kid, [...] it’s a real winner.
1948		D. Dodge Bullets For The Bridegroom (1953) 14: I’m happy to meet you, young lady. Always knew Whit would get himself a winner.
1952		K. Amis letter 8 Sept. in Leader (2000) 291: The grammar-school touch is a winner.
1959		L.P. Boone ‘Gator Sl.’ AS XXXIV:2 154: A winner is successful both academically and socially; he is a popular, all-round, well-dressed, up-to-date student.
1965		G. Melly Owning Up (1974) 143: All it [i.e. a game] consisted of was deciding whom among your friends and acquaintances were ‘winners’ and who were ‘losers.’.
1978		L. Kramer Faggots 109: ‘Not bad,’ Durwood said. ‘A winner.’.
1986		F. Taylor Auf Wiedersehen Pet Two 223: He knew he was on to a winner.
1999		K. Sampson Powder 53: He was an arrogant prick, but he was a winner and he’d drag them all with him.

2. (US campus) used ironically, a social outcast, i.e. a loser n. (1)

1965		P. Wylie Esquire July 44–45: winner — one who is ‘out-of-it’ or is unattractive; commonly phrased as ‘a real winner.’.
1973		L. Shecter On the Pad 245: ‘We sit there, Murray, Finelli, me and this broad who was a real winner. A nitwit. She was like in a trance’.