Plain English Meaning
The official limits on how, where, and when an aircraft can be operated, based on what it has been proven to do during testing. These limits tell the pilot whether a planned flight is within the aircraft's capability for the conditions of the day.
Full Definition
The performance-based restrictions placed on an aircraft's operation, derived from flight testing and certification, that define the conditions under which the aircraft can be flown safely and legally. These limitations cover takeoff and landing distances, climb performance, weight, altitude, temperature, runway requirements, and obstacle clearance, and are published in the Aircraft Flight Manual (AFM) or Pilot's Operating Handbook ().