sump

A hollow or pit into which liquid drains, such as a cesspool, cesspit or sink.

The lowest part of a mineshaft into which water drains.

A completely flooded cave passage, sometimes passable by diving.

The crankcase or oil reservoir of an internal combustion engine.

The pit at the lowest point in a circulating or drainage system (FM 55-501).

An intentional depression around a drain or scupper that promotes drainage.

Of a cave passage, to end in a sump, or to fill completely with water on occasion.

“This low passage sumps quickly after moderate rainfall.”