*injector*

n. 1. One who, or that which, injects. [ 1913 Webster ]

2. (Mach.) A contrivance for forcing feed water into a steam boiler by the direct action of the steam upon the water. The water is driven into the boiler by the impulse of a jet of the steam which becomes condensed as soon as it strikes the stream of cold water it impels; -- also called Giffard's injector, from the inventor.

fuel injector, a device for actively injecting fuel into an internal-combustion engines by directly forcing the liquid fuel into the combustion chamber at an appropriate point in the piston cycle; -- an alternative to a carburetor, in which an air-fuel mixture is drawn in by the downward stroke of the piston. [ 1913 Webster ]