Plain English Meaning
A flat, cleared strip of ground around the runway designed to give an aircraft a survivable surface if it lands short, runs off the end, or veers off the side.
Full Definition
A defined surface surrounding the runway, prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway. It is graded, cleared of hazardous objects, and capable of supporting an aircraft and emergency vehicles under normal conditions.
Context Anchor
You will see this term in airport design, airport diagrams, safety discussions, and reports about runway overruns or runway excursions.