Definition: A window sash is the framed part of the window which holds the sheets of glass in place. Most commonly, though, window sash refers to that part of the window which moves.
Window sashes are typically found in the double-hung window style, in which one sash is positioned above a lower sash. The lower window sash has the capacity to slide vertically until it is nearly parallel with the upper sash.
If the window sash breaks, it is possible to purchase a sash replacement kit. This avoids the cost and mess of total window replacement. Also, because it is designed for homeowners to be able to use, it helps avoid labor costs associated with window or sash replacement.
Examples: After the McClearys' window broke, they found that they were able to remove the sash portion and have that replaced, saving considerable money.