underworld

n.

阴间，地狱；下流社会；（地球另一面的）对跖点；地球

1. Drug traffic is controlled by the underworld.
   毒品生意为黑社会所控制。
2. He looked like a shifty underworld character.
   他看起来是个鬼头鬼脑的下流社会的角色。
3. My knowledge of the denizens of the underworld is unmatched.
   没人比我更了解这些下层社会的居民。

The interpersonal underworld
Codes of the Underworld:How Criminals Communicate
Codes of the underworld: how criminals communicate
Petroleomics: Chemistry of the underworld
The "Underworld"in a Territorial Sparrow: Adaptive Strategy for Floaters
Inside Cyber Warfare: Mapping the Cyber Underworld
Inside Cyber Warfare: Mapping the Cyber Underworld
Street justice: Retaliation in the criminal underworld
Player modeling using self-organization in tomb raider: underworld
Wages of Crime: Black Markets, Illegal Finance, and the Underworld Economy