Plain English Meaning
A special crushable surface built at the end of some runways. If a plane runs off the end, the surface crumbles under the wheels and stops the plane safely.
Full Definition
A paved area at the end of a runway made of crushable material designed to safely decelerate an aircraft that overruns the runway. The aircraft's wheels sink into the material, which absorbs energy and brings the aircraft to a stop with minimal damage.
Context Anchor
You will see this term in runway safety, airport layout, and EMAS discussions, especially when learning what is installed beyond some runway ends.
Derivation
From 'arrest' (to stop) and 'bed' (a layer of material). The name describes exactly what it does: a layer of material that arrests the aircraft.