Plain English Meaning

The most power the engine is allowed to produce in that situation, according to the airplane's official handbook. Going above it can damage the engine or break operating rules; staying below it may not give the airplane the performance it needs.

Full Definition

The highest engine power setting permitted by the airplane's manufacturer for a given phase of flight or condition, as published in the Pilot's Operating Handbook (POH) or Airplane Flight Manual (AFM). For takeoff in most piston-engine airplanes, this typically means full throttle with mixture and propeller controls set as specified for the .