Which term describes an unexpected event that may cause injury?

The term that describes an unexpected event that may cause injury is "accident." An accident refers to an unforeseen and unintentional event that results in damage or injury. This term is commonly used in various contexts, including medical settings, to indicate incidents that occur suddenly and without warning, often leading to harm or adverse effects on individuals.

In contrast, while an incident can refer to an occurrence, it does not specifically imply injury; it could be neutral or even positive. Trauma typically refers to the physical or psychological injury resulting from an accident or other disruptive events, rather than the event itself. An emergency denotes a serious, unexpected situation requiring immediate action, which may or may not be the result of an accident. Thus, the specificity of "accident" to denote an unexpected event causing injury makes it the correct term in this context.