Impeller

Impeller

An impeller is a driven rotor used to increase the pressure and flow of a fluid.  It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid.

Strictly speaking, propellers are a sub-class of impellers where the flow both enters and leaves axially, but in many contexts the term "impeller" is reserved for non-propeller rotors where the flow enters axially and leaves radially, especially when creating suction in a pump or compressor.