a sump on a boat is the bilge. In the human eye, the vitreous humour has a minor role as a metabolic sump. In caving/potholing terminology, a sump is a permanently flooded section of a cave, such that the caver must submerge under water to reach the other side. Other uses In a foxhole, a grenade sump is a deeper hole dug inside the foxhole into which live grenades can be kicked to minimize damage from the explosion. In medieval cosmology, the sump was the center of the cosmos, where the dregs and filth descended, with the celestial sphere far exalted above the world of fallen man. See also References Architectural elements Engine components