‘敲门’ literally means ‘to strike a door’ — ‘敲’ (qiāo) means ‘to knock, tap, or strike,’ and ‘门’ (mén) means ‘door.’ Together, they form a common verb meaning ‘to knock on a door,’ used when someone signals their presence before entering a room, house, or office. It’s a polite and expected action in Chinese culture, especially before entering private spaces like bedrooms or offices.

The phrase is almost always used as a verb in the predicate position and can be modified by aspect particles like ‘了’ (le), ‘过’ (guò), or ‘在’ (zài). It does not function as a noun or adjective. While ‘敲’ alone can mean ‘to knock’ on various surfaces (e.g., a table), ‘敲门’ specifically refers only to knocking on doors — never on walls, windows, or other objects. It’s neutral in register and appropriate for both formal and informal speech.