Plain English Meaning
The band of altitudes where the pressurization system can hold the cabin at one steady chosen pressure, no matter how high or low the airplane is flying within that band.
Full Definition
The range of flight altitudes through which a pressurization system can maintain a selected, constant cabin altitude regardless of changes in the aircraft's actual altitude. Within this range, the cabin pressure stays fixed even as the airplane climbs or descends.
Context Anchor
Seen in discussions of pressurized aircraft, cabin altitude, and how the pressurization system manages pressure during and high-altitude flight.