noun
A heavy curtain used to block light completely, often for photography, theater, or sleeping during the day.
写真を撮るために、窓に暗幕をかけた。
I put up a blackout curtain over the window to take photos.
夜勤の後は、暗幕を閉めて昼間でも真っ暗にして寝ます
After the night shift, I close the blackout curtain and sleep in total darkness even during the day.