Subterráneo (en. Underground)
/sub.teˈra.ne.o/
Slang Meanings
Hidden or secret, related to clandestine activities.
It is said that he has a subterranean business that no one knows about.
Se dice que tiene un negocio subterráneo que nadie conoce.
Referring to something that is out of sight, generally illegal.
The underground market for stolen goods is very active.
El mercado subterráneo de productos robados es muy activo.