sump (n.) Look up sump at Dictionary.com
mid-15c., "marsh, morass" (from mid-13c. in place names), from Middle Dutch somp or Middle Low German sump, from Proto-Germanic *sumpaz, from PIE *swombho- "spongy." Meaning "pit to collect water" is first found 1650s. Sump-pump (1884) originally was in mining.