hideout; secret base; safe house
Refers to a concealed location used by a group for clandestine activities, often with a nuance of illegality or secrecy. Commonly used in contexts involving criminals, spies, or rebels.
from English agitating point · from Russian agitpunkt
The organization had set up a hideout deep in the mountains.
The police tracked down the criminal's hideout.
The spies planned their next operation at the secret base.
The suspect is believed to have been hiding out in a secret base.
The police finally tracked down the terrorist group's hideout.
The Metropolitan Police Department raided the drug-dealing group's hideout.
巣 in its figurative sense means a hideout for people with shared (often shady) interests, while アジト is a more modern loanword specifically for a secret hideout or base of operations.
Borrowed from Russian агитпункт (agitpunkt, 'agitation point'), originally a Soviet term for a local political propaganda center. In Japanese, the meaning shifted to a secret hideout or base of operations, likely through association with clandestine revolutionary activities.