The act or process of drifting; the state of being carried along by currents of air or water. The driftage of the boat was caused by the strong ocean currents.
Material or debris that has been carried along by wind or water. The beach was littered with driftage after the storm.
The lateral deviation or distance by which a vessel, aircraft, balloon, etc., is carried off course by wind or current. The navigator calculated the driftage of the aircraft to correct its heading.