A small door; a gate, esp. one in a larger gate or door.

小门；便门；侧门。

Small window, often with a grating, as in a ticket office.

小窗口(如售票口)。

In cricket, either of the two frames at which the ball is bowled.

板球戏之三柱门。

In croquet, arch through which the ball must be hit.

槌球戏之拱门。