Forcer

noun

1. One who or that which forces, drives, compels, or constrains.
2. Specifically— In mech., a solid piston applied to a pump for the purpose of producing a constant stream, or of raising water to a greater height than it can be raised by the pressure of the atmosphere. See pump.
3. In Cornish mining, a small pump worked by hand, used in sinking small simples or pits.
4. A chest; a coffer.
5. One who, or that which, forces or drives.