Green’s Dictionary of Slang

1. strong, muscular, healthy, good-looking.

1985		T.R. Houser Central Sl. 12: buff To be muscularly well-developed. [Ibid.] 53: ‘Nigger all hunched, think he buff, think he down.’.
1999		Guardian Weekend 9 Oct. 3: The body’s still buff.
2004		C. Hiaasen Skinny Dip 283: Chaz had been pleased about how buff he looked.
2005		Jade LB Keisha the Sket (2021) 21: ‘Dat bwoi iz 22 buff!’.
2007		L. Redhead Cherry Pie [ebook] [He] exchanged a few words with the buff dude at the front desk.
2015		J. Stahl OG Dad 71: He’s a buff, young fellow, kind of astronautish.

2. sexy, attractive.

2006		G. Malkani Londonstani (2007) 50: Samira Ahmed ain’t nuffink special [...] my bum is buffer than her.
2008		A. Wheatle Dirty South 10: I could just about get along with my life without Akeisha’s buff self invading my mind.
2010		BBC News ‘Report on Teenage Slang’ 11 Mar. [radio] John’s chick is proper buff [...] John’s girlfriend is really pretty.
2017		hubpages.com ‘Roadman Slang 4 Jun. 🌐 Buff - attractive, used to describe a male or female. This word is usually earnest and said in awe, from girls to other girls (‘you're so buff’), but it is also casual and not too flattering. In other words, you could tell someone that they were ‘buff’ without seeming like you were putting them on a pedestal.
2020		G. Krauze What They Was 210: [T]hat boy’s buff.
2021		J. Ellroy Widespread Panic 191: Three hunky monkeys [...] buff B-boys.
2024		J. Meades Empty Wigs (t/s) 749: ‘[Y]ou can’t be an escort unless you’re toney and buff and not a KFC jumbo bucket’.

3. (UK black) in fig.senses, first-rate, e.g. of drugs.

2020

G. Krauze What They Was 102: Make sure it’s buff yeah [...] I know you got that lemon [haze] .