In room-and-pillar mining, to extract a deposit of rock by breaking down a pillar which had been holding it in place.
To engage in the recreational exploration of caves.
To hollow out or undermine.
To surrender.
To collapse.
look out!; beware!
A code cave.
A hole, depression, or gap in earth or rock, whether natural or man-made.
A large, naturally-occurring cavity formed underground or in the face of a cliff or a hillside.
A shielded area where nuclear experiments can be carried out.
A storage cellar, especially for wine or cheese.
A place of retreat, such as a man cave.
A naturally-occurring cavity in bedrock which is large enough to be entered by an adult.
Debris, particularly broken rock, which falls into a drill hole and interferes with drilling.
A group that breaks from a larger political party or faction on a particular issue.
A collapse or cave-in.
The vagina.
To provide with a penthouse, shelter by means of a shed sloping from a wall, or anything similar.
Any of the sloping roofs at the side of a real tennis court.
An outhouse or other structure (especially one with a sloping roof) attached to the outside wall of a building, sometimes as protection from the weather.
An apartment or suite found on an upper floor, or floors, of a tall building, especially one that is expensive or luxurious with panoramic views. Sometimes these are located just under "penthouse mechanical" floors.