(US black) a police officer, esp. a member of the drugs squad.
|DAUL 119/1: Knock-man. A policeman; an informer; a complaining witness in criminal proceedings.et al.|
|Clockers 4: The white guy [...] looked too twitchy and scared to be a knocko.|
|Corner (1998) 16: Plainclothesmen. Knockers. Six police jump out of two unmarked Chevrolets.|
|Wire ser. 1 ep. 2 [TV script] Western [Baltimore] knockos come around here, picking shit up off the ground.‘The Detail’|