a doctor who works in a hospital in casualty (= the hospital department where people who are hurt in accidents or suddenly become ill go for urgent treatment) and is trained to deal with accidents or sudden illness: It was my day off after a busy week as a casualty officer in an inner-city hospital. The Central casualty service is the face of the hospital and its main pillars. It provides 24 hours services for all emergency cases which include any acute illness and cases which patients and their relatives consider to be attended urgently.