Green’s Dictionary of Slang

rank adj.1

[ext. uses of SE rank, rancid, rotten, coarse or indecent]

1. [late 17C+] (also ranky) foul-smelling.

2. [mid-18C+] (also rank-ass) second-rate, inferior, disgusting; also as intensifier.

3. [20C+] (W.I.) impertinent, extremely cheeky.