- an accident, esp. a fatal one
- a member of the armed forces who is lost to active service through being killed, wounded, captured, interned, sick, or missing
- [pl.] losses of personnel resulting from death, injury, etc.
- anyone hurt or killed in an accident
- anything lost, destroyed, or made useless by some unfortunate or unforeseen happening
Origin of casualtyMiddle English and Old French casuelte from Medieval Latin casualitas: see casual