Plain English Meaning
A pump driven by the engine that moves air through the aircraft's air-powered systems, such as the rubber boots that inflate to crack ice off the wings.
Full Definition
An engine-driven pump that supplies the airflow used by certain aircraft systems, including pneumatic deice boots on the wings and tail. It either pulls air in (suction/vacuum) or pushes it out (pressure), depending on system design, providing the air pressure needed to inflate and deflate the boots that break ice off the leading edges.