Green’s Dictionary of Slang

bad-ass n.

[SE bad + -ass sfx]

1. (US) an unpleasant, aggressive individual; thus superlative baddest ass n.

[US]D. Howard ‘USMC Sl.’ AS XXXI:3 191: A marine who postures toughness is sarcastically labeled a bad ass or hairy-assed marine.
[US](con. early 1950s) J. Peacock Valhalla 303: You’re a real bad ass.
[US](con. 1950s) H. Junker ‘The Fifties’ in Eisen Age of Rock 2 (1970) 101: The J.D.’s emerged [...] Badass.
[US]P. Hamill Flesh and Blood (1978) 47: I’m beginning to look like a bad-ass. I went to the barber and got a crew cut, and it made me look even tougher.
[US]J.L. Gwaltney Drylongso 232: In heaven, when the deal go down it’s the blackest and the baddest ass that makes the others deuce out.
[US](con. 1968) Bunch & Cole Reckoning for Kings (1989) 289: Bikers got big hearts, you know? Like we just pretend to be bad asses.
[US](con. 1970s) G. Pelecanos King Suckerman (1998) 36: Jealous boyfriends and barroom bad-asses and all the rest.
Ariano & Sternbergh Hey! It’s That Guy! 1989: When you have more than one character on your resume who’s named after a kind of lethal blade, then chances are, you’re a bad-ass.

2. (US) on bad = good model, a tough, admirable individual; also occas. metonymic for one’s whole body.

[US]D. Ponicsan Last Detail 2: Bad-Ass, wake up, it’s way the hell past reveille.
[US]B. Jackson Get Your Ass in the Water 57: Dolomite is the ultimate badass: he drinks, fights, and fucks, and in between seems to brag about what he has just done or will do next.
[US](con. 1968) D.A. Dye Citadel (1989) 238: Glad to find out the badass was still alive.
[US]D. Woodrell Muscle for the Wing 132: He occupied an exalted spot against the wall, surrounded by lesser badasses.
[US]S. Morgan Homeboy 95: He obliged the ironbarred gallery with the Homeric ballad of that badass Dolomite.
[US]S. King Dreamcatcher 9: You want to hurry your bad ass back.
[US]F.X. Toole Pound for Pound 120: Everyone would know he was a badass.
[US]A. Steinberg Running the Books 4: A book-slinger with a badge and a streetwise attitude, part bookworm, part badass.
[US]D. Winslow The Force [ebook] They’re badasses [...] always ready to go, ready to dance, just for the fuck of it.

3. (US black) an untrustworthy male.

[US]E. Folb Runnin’ Down Some Lines 148: A number of terms were used to characterize the young man who could not be trusted [...] bad-ass, no-account nigger.
[US]N. Green Shooting Dr. Jack (2002) 230: Got seven or eight former badasses in there with broken ribs.

In derivatives

badassery (n.)

the qualities implicit in sense 2.

in Assembly on Literature for Adolescents Rev. 30-31 210/2: I can SEE myself getting dragged into a whole heap of BADASSery.
[US]Spin Dec. 118: The Donnas’ Grease-lubed vision of badassery — dressing trashy, talking dirty, and putting out .
A. Hansen Weather Man [ebook] I still had a little badassery to my look. I mean, come on. I’m Dan Fucking Weatherly. I’m badassery personified, costume party or not.
[US]Eble UNC-CH Campus Sl. Spring 2014 1: BADASSERY — qualities of a bad ass, i.e., skilled, stylish, cool: ‘Marcus Paige’s basket at the buzzer was badassery at its height.’.