A small cavern or hollow place in the side of a hill, or among rocks; esp., a cave used by a wild beast for shelter or concealment; as, a lion's den; a den of robbers.
- The shelter or retreat of a wild animal; a lair.
- A cave or hollow used as a refuge or hiding place.
- A hidden or squalid dwelling place: a den of thieves.
- A secluded room for study or relaxation.
- A unit of about eight to ten Cub Scouts.
- To inhabit or hide in a den.