Green’s Dictionary of Slang

bad-ass adj.

[bad-ass n.; given the use of bad, the term is as much congratulatory as not]
(orig. US black)

1. [1950s] unpleasant.

2. [1950s+] (also ass-bad, bad-arse, bad-assed) tough, aggressive, frightening.

3. [1970s+] of people, animals, objects: formidable, admirable, first-rate.

In compounds