cesspool excavation in the bottom of a drain to retain solid matter XVII; well to receive soil from privies, etc. XVIII. perh. alt., with assim. to POOL 1, of cesperalle, susprall, suspirel settling tank, cesspool (XVI), vars. of †suspiral vent, esp. of a conduit, water-pipe — OF. souspirail (mod. soupirail) air-hole, f. sou(s)pirer (L. suspīrāre) SUSPIRE + L. spiraculum air-hole.
Hence cesspit XIX.

cess·pool / ˈsesˌpoōl/ • n. an underground container for the temporary storage of liquid waste and sewage. ∎ fig. a disgusting or corrupt place.