noun · a controlled passage for entry or exit, such as a boarding gate, customs post, or toll station

旅客请到五号闸口准备登机。

noun · a figurative access point or strategic entrance

这座城市是通往西南地区的闸口。

noun · a gate or opening for controlling the flow of water

工人们正在修理水库的闸口。

noun · area in the Shangcheng district of Hangzhou

闸口位于杭州市上城区，地处钱塘江北岸。