The firemen used the pumper to extinguish the fire.
The definition of a pumper is a fire engine with a hose, pumps and water.
A big red fire engine that comes to your house to put out a fire and that has a hose, pump and water tank on board used to put out that fire is an example of a pumper.
- a person or thing that pumps
- a fire truck that carries hose and a water tank and can pump water under great pressure