Constant-displacement pump
A fluid pump that moves a specific volume of fluid each time it rotates; the faster the pump turns, the more fluid it moves. Some form of pressure regulator or relief valve must be used with a constant-displacement pump when it is driven by an aircraft engine.
Also defined in 1 more source
A fluid pump that moves a specific volume of fluid each time it rotates.
Aviation Maintenance Technician Handbook — Powerplant, p. G-8