急诊 (jí zhěn) literally combines 急 (jí), meaning 'urgent' or 'immediate', and 诊 (zhěn), meaning 'diagnosis' or 'medical examination'. Together, they form a noun referring to emergency medical treatment — care provided for sudden, serious, or life-threatening conditions that require immediate attention. It is commonly used in healthcare contexts, especially in hospitals where the 'emergency department' is called 急诊室 (jí zhěn shì).

This term emphasizes speed and urgency, distinguishing it from routine or scheduled medical visits (e.g., 门诊, mén zhěn). It applies to both the service itself and the department offering it. While often associated with accidents or acute illnesses like heart attacks or severe allergic reactions, it may also cover urgent mental health crises or complications during pregnancy. In everyday speech, people say 我要去急诊 (Wǒ yào qù jí zhěn) — 'I need to go to the emergency room' — indicating immediacy and seriousness.