Green’s Dictionary of Slang

1. (US) a person or thing that beats or excels others.

1845		S. Judd Margaret 283: Take it by and large [...] and she is the beater of all .
1886		Harper’s Mag. Nov. 835/1: Well, for getting sunthin outer northing, she’s a beater! [DA].
1908		H. Green Maison De Shine 263: Ain’t she a world beater?

2. a beaten up vehicle, also attrib.

1980		A. Rule Stranger Beside Me 18: When he'd stolen the ‘beater’ off the streets in Glenwood Springs, he'd known it might not be up to making the snow-clogged pass into Aspen.
1986		L. Heinemann Paco’s Story (1987) 187: Getting into Marty-boy’s rusted-out beater of a Mustang.
1999		N. Stephenson Cryptonomicon 363: I traded in my old beater pickup truck for a minivan.
2000		M. Dibdin Thanksgiving 121: She was parking this real beater, a white Toyota Corolla from way back, dented all over.
2011		D.R. Pollock Devil All the Time 96: A couple of banged-up beaters sat in the parking lot.
2013		C. Dundas ‘Rightful King of Wrestling’ in ThugLit Nov.-Dec. [ebook] We drove down in my beater Caddie.
2020		D. Winslow ‘Sunset’ in Broken 190: [I]n addition to the beater car, he sports a black goatee.

3. (UK black/gang) a gun, a revolver.

2017		Unknown T ‘Bop with Smoke’ 🎵 Ain't no repercussions been taken / Bitch boy lucky the beater got taken.
2022		Digga D. ‘Little Big Boss’ 🎵 When they [i.ed. the police] need assistance, I throw away the beater.