This noun refers to an opening in a wall or roof, usually fitted with glass, to let in light or air and allow people to see out. You can open and close a 窓. For example: 窓を開けてください。(Please open the window.)

壁(かべ)にある、外(そと)が見(み)えたり光(ひかり)が入(はい)る部分(ぶぶん)です。例(たと)えば：窓(まど)を開(あ)けてください。