Meaning

• A small cavern or hollow place in the side of a hill, or among rocks; especially, a cave used by a wild animal for shelter or concealment.

  "Daniel was put into the lions’ den."

• A squalid or wretched place; a haunt.

  "a den of vice"

• A comfortable room not used for formal entertaining.

• A narrow glen; a ravine; a dell.

Meaning

• To ensconce or hide oneself in (or as in) a den.