sump

Etymology

From Middle English sompe, either from Middle Dutch somp, sump or Middle Low German sump from Old Saxon *sump, from Proto-West Germanic *sump, ultimately from Proto-Germanic *sumpaz. See swamp.

noun

1. A hollow or pit into which liquid drains, such as a cesspool, cesspit or sink.
2. The lowest part of a mineshaft into which water drains.
3. A completely flooded cave passage, sometimes passable by diving.
4. (automotive) The crankcase or oil reservoir of an internal combustion engine.
5. (nautical) The pit at the lowest point in a circulating or drainage system (FM 55-501).
6. (construction) An intentional depression around a drain or scupper that promotes drainage.

verb

1. (intransitive) Of a cave passage, to end in a sump, or to fill completely with water on occasion.
   We discovered a new passage, but it sumped after 100 metres.
   This low passage sumps quickly after moderate rainfall.