The term FRENCH DOOR PART can be summarized as a window PANE, which is a four-letter word. French doors are a type of door typically used in homes and other buildings that have two parts that open outward from the center. The part of the French door that is made of glass is referred to as a window PANE. Window panes are usually made of a single sheet of glass, but can also be made of multiple sheets of glass held together by a frame.