1. (noun)sump an oil reservoir in an internal combustion engine Synonyms: sink, cesspool, cesspit
2. (noun)sump a well or other hole in which water has collected Synonyms: sink, cesspool, cesspit
3. (noun)cesspool, cesspit, sink, sump a covered cistern; waste water and sewage flow into it Synonyms: sump, sinkhole, sink, cesspool, cesspit, swallow hole