The definition of a casualty is a serious accident.(noun)
A fatal car crash is an example of a casualty.
Casualty is defined as a person or thing lost or destroyed by an accident or military action.(noun)
See casualty in Webster's New World College Dictionary
noun pl. casualties
Origin: ME & OFr casuelte < ML casualitas: see casual
See casualty in American Heritage Dictionary 4
noun pl. ca·su·al·ties
Origin: Middle English casuelte
Origin: , from Old French
Origin: , from Medieval Latin cāsuālitās, chance, accident
Origin: , from Latin cāsuālis, fortuitous; see casual.
Learn more about casualty