Plain English Meaning
How well an airplane is built to keep the people inside alive and uninjured if it crashes.
Full Definition
The capacity of an aircraft's structure, restraints, seats, and interior design to protect occupants from injury during an impact by absorbing and dissipating crash forces, maintaining a survivable space around occupants, and reducing the risk of post-crash fire.
Context Anchor
Seen in discussions of aircraft design, seat belts and shoulder harnesses, emergency landings, and survivable accidents.
Derivation
A combination of 'crash' and 'worthiness' (meaning 'fitness' or 'suitability for'). The same pattern as 'seaworthiness' (fit to handle the sea) or 'airworthiness' (fit to fly). So 'crashworthiness' literally means 'fit to handle a crash' -- built to perform well in one.
Why Pilots Care
It influences survival rates in accidents through choices in seat design, , and restraint .