1.NounSomething which or someone who impels.
A rotating component of a device that accelerates fluid, increasing its pressure or flowrate.
"screw impeller"
2.NounA rotating component of a device that accelerates fluid, increasing its pressure or flowrate.
"screw impeller"
3.NounEspecially, such a component that drives the fluid radially (outward from a center of rotation) rather than axially. (Impellers are found in devices such as pumps, water jets, washing machines, and agitated tanks.)