Green’s Dictionary of Slang

comer n.

[SE come (on), to advance (in one’s aims, development)]

1. (orig. US) an ambitious, go-ahead person, ‘the coming man’.

[US]H. Palmer Base Ball Field 91: He piled up error after error, but Dan said he was a ‘comer’ [OED].
[US]Ade Forty Modern Fables 2: [He] was pointed out as a Comer in the Business World.
[US]S. Ford Shorty McCabe 8: I dropped into the only thing I knew how to do, trainin’ comers to go against the champs.
[US]G. Bronson-Howard Enemy to Society 330: When it comes to talkin’, anybuddy ’ud think Jeffries was still a ‘comer’!
[US](con. 1910s) S. Lewis Elmer Gantry 289: I want this man — he’s a comer — he’d be useful to me.
[US]W.R. Burnett Iron Man 25: He’s a comer, Coke. He looks clumsy but he’s fast.
[US]N. Algren ‘Depend on Aunt Elly’ in Texas Stories (1995) 104: The kid was one of those soldiers’ champions who’d looked like a comer around the camp PX.
[US]Pittsburgh Courier (PA) 8 Apr. 20/1: What’s to become of the comer, the younger struggling performers who are trying to make their way.
[UK]G. Kersh Fowlers End (2001) 238: Now this I call nishertive. You’re learning, Daniels, you’re a comer.
[US]‘Tom Pendleton’ Iron Orchard (1967) 108: Boyd Hallam [...] who Hoss described as a ‘real comer’.
[US]R. Campbell Alice in La-La Land (1999) 129: Bama was twenty-seven and a comer. His foot was on the ladder.
[UK]Guardian Guide 12–18 June 7: Fraser’s a real comer.

2. (US) a business, club or project promising success.

[US]Phila. Eve. Bulletin 9 Sept. 41: He said the club [the New York Yankees] is a comer [ W&F].