A single light frame containing one or more lites of glass.
Merriam-Webster Online Dictionary
sash (noun) a band worn about the waist or over one shoulder and used as a dress accessory or the emblem of an honorary or military order
the framework in which panes of glass are set in a window or door , also such a framework together with its panes forming a usually movable part of a window
sash (Wikipedia)
A painting of Captain Kidd with a red sash around his waist.
A sash is a large and usually colorful ribbon or band of material worn around the body, draping from one shoulder to the opposing hip, or else running around the waist. The sash around the waist may be worn in daily attire, but the sash from shoulder to hip is worn on ceremonial occasions only. Ceremonial sashes are also found in a V-shaped format, draping from both shoulders to the stomach like a large necklace.