(Mimarlık) In architecture, a transom is the term given to a transverse horizontal structural beam or bar, or to the crosspiece separating a door or the like from a window above it, as opposed to a mullion which refers to a vertical structural member. Transom is also the customary U.S. word used for a transom light, the window over this crosspiece. In Britain, the 'transom light' above a door is usually referred to as a "fanlight" if a semi-elliptical shape, and occasionally as an "overlight" or "hopper", or by the French word "vasistas"
1 A horizontal bar of wood or stone across a window 2 The cross-bar separating a door from the window, panel, or fanlight above it 3 The window above the transom bar of a door
A small opening above a door or window separated by a horizontal member that usually contains a sash or a louver panel hinged to the transom bar Transoms, or fan lights, were first used in the 18th century on exterior doors They increased the amount of light let into the front hall, and because of them, the size of the front door could be reduced They probably encouraged the Victorian use of stained glass for front doors
A horizontal transverse beam or bar in a frame; a crosspiece separating a door or the like from a window or fanlight above it Also, a window above a door or other window, built on and commonly hinged to a transom