also: サッシュ
noun
sash; sliding window frame
In Japanese, primarily refers to the metal frame of a sliding window or door, not a fabric sash. The English word 'sash' can also mean a fabric band, but that is not the primary meaning in Japanese.
新しいサッシに交換したら、部屋がずいぶん暖かくなった。
After replacing the window frames with new sashes, the room became much warmer.
このマンションはサッシが古くて、すきま風が入る。
The window sashes in this apartment are old, so drafts come in.