sinkhole

A natural depression in a land surface communicating with a subterranean passage, generally occurring in limestone regions and formed by solution or by collapse of a cavern roof.

A hole formed in soluble rock by the action of water, serving to conduct surface water to an underground passage

A depressed area in which waste or drainage collects.

A hole in the playfield that rewards the player when the ball is guided into it.

a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof