louvered window
A window fitted with horizontal slats (louvers) that allow ventilation while blocking rain and direct sunlight. Common in Japanese architecture.
この家の浴室には鎧窓が付いていて、風通しが良い。
This house's bathroom has a louvered window, so ventilation is good.
Compound of 鎧 (yoroi, 'armor') and 窓 (mado, 'window'), likely from the resemblance of the slats to armor plates.