small window; fenestella; scuttle
General term for a small window. Also used in architecture for a small window-like opening (fenestella) and in nautical contexts for a small hatch or scuttle on a ship.
This room has only one small window.
I could see the waves outside through the ship's scuttle.
Compound of 小 (こ, 'small') and 窓 (まど, 'window').