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.
Synonym of fort (“structure improvised from furniture, etc. for playing games.”)
A comfortable room not used for formal entertaining.
A group of Cub Scouts of the same age who work on projects together.
A squalid or wretched place; a haunt.
To ensconce or hide oneself in (or as in) a den.
Regions beneath the surface of the earth, both natural (eg. caves) and man-made (eg. mines).
A movement or organisation of people who resist artistic convention.
A movement or organisation of people who resist political convention.
Synonym of subway: a railway that is under the ground.
To route electricity distribution cables underground.
Hidden, furtive, secretive.
Below the ground; below the surface of the Earth.
Outside the mainstream, especially unofficial and hidden from the authorities.
Below the ground.
Secretly.