/sump/ , n.
1. a pit, well, or the like in which water or other liquid is collected.
2. Mach. a chamber at the bottom of a machine, pump, circulation system, etc., into which a fluid drains before recirculation or in which wastes gather before disposal.
3. Mining.
a. a space where water is allowed to collect at the bottom of a shaft or below a passageway.
b. a pilot shaft or tunnel pushed out in front of a main bore.
4. Brit. crankcase.
5. Brit. Dial. a swamp, bog, or muddy pool.
[ 1375-1425; late ME sompe sump; c. G Sumpf; akin to SWAMP ]