■ noun
1》 the base of an internal-combustion engine, which serves as a reservoir of oil for the lubrication system.
2》 a depression in the floor of a mine or cave in which water collects.
3》 a cesspool.
Origin
ME (in the sense 'marsh'): from MDu. or Low Ger. ~ , or (in the mining sense) from Ger. Sumpf ; related to swamp .