What is the definition of "absolute ceiling" in aviation?

The absolute ceiling in aviation is defined as the maximum altitude at which level flight can be sustained. At this altitude, the aircraft can no longer maintain altitude in level flight because the aircraft's engine power and lift are insufficient to overcome weight and drag. Beyond this point, even if the pilot tries to maintain level flight, the aircraft will begin to descend.

Understanding this concept is crucial for pilots, as flying above the absolute ceiling can lead to a loss of control due to insufficient performance capabilities. The other definitions pertain to different aspects of aircraft performance, such as drag or endurance, but they do not accurately describe the specific trait of the absolute ceiling. This makes the correct understanding of the absolute ceiling vital for safe operating practices in aviation.