That which comes without design or without being foreseen; contingency.
- An accident, especially one involving serious injury or loss of life.
- One injured or killed in an accident: a train wreck with many casualties.
- One injured, killed, captured, or missing in action through engagement with an enemy. Often used in the plural: Battlefield casualties were high.
- One that is harmed or eliminated as a result of an action or a circumstance: The corner grocery was a casualty of the expanding supermarkets.