gate door; doors of a gate
Refers specifically to the door or leaf of a gate, often a large or formal entrance. More precise than 門 (gate) alone.
門扉を閉めてください。
Please close the gate door.
古
The guard opens the gate door early in the morning.
The old gate door creaked.
夜になると門扉を閉める。
The gate door is closed when night falls.
The gate door is designed to open automatically.
Construction to install a new gate door has begun.
扉 is the general word for any hinged door leaf, while 門扉 narrows this to the leaf of a gate specifically.
Used because 門扉 (gate doors) are flat, panel-like objects, like a 扉 (door).
Compound of 門 (gate) and 扉 (door). The reading もんぴ is a standard on'yomi combination.