noun
passenger entrance; boarding gate
Refers to the designated entrance for passengers at a train station or similar transport hub.
駅の乗車口で切符を確認された。
My ticket was checked at the station's passenger entrance.
noun
passenger door
Refers to the door through which passengers board a train, bus, or similar vehicle.
バスの乗車口は前のドアです。
The bus's passenger door is the front door.