1.
back gate; rear entrance
The gate or entrance at the back of a building, school, temple, or other property. Contrasts with 正門 (main gate) or 表門 (front gate).
Usage
Contrasts with 正門 (main gate) and 表門 (front gate). Schools, temples, and large properties typically have both a main gate and a back gate. Sometimes used figuratively to mean a backdoor route or shortcut.