1 [C] a person who is killed or injured in a war or an accident 伤亡者: After the accident the casualties were taken to hospital. 意外发生之后，伤亡者被送往医院。

2 [C] a person or thing that suffers as a result of sth else 受害者: Many small companies became casualties of the economic crisis. 很多小公司成了这次经济危机的受害者。

3 (also casualty department) (US 美 eˈmergency roomER) [U] the part of a hospital where people who have been injured in accidents are taken for immediate treatment 急救室；急诊室