architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing buildings ...

, a transom is a transverse horizontal structural beam or bar, or a crosspiece separating a door from a window above it. This contrasts with a

mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid sup ...

, a vertical structural member. Transom or transom window is also the customary U.S. word used for a transom light, the window over this crosspiece. In Britain, the transom light is usually referred to as a

fanlight A fanlight is a form of lunette window, often semicircular or semi-elliptical in shape, with glazing bars or tracery sets radiating out like an open fan. It is placed over another window or a doorway, and is sometimes hinged to a transom. ...

, often with a semi-circular shape, especially when the window is segmented like the slats of a folding hand fan. A prominent example of this is at the main entrance of

10 Downing Street 10 Downing Street in London, also known colloquially in the United Kingdom as Number 10, is the official residence and executive office of the first lord of the treasury, usually, by convention, the prime minister of the United Kingdom. Along w ...

, the official residence of the British prime minister.

History

In early Gothic

ecclesiastical {{Short pages monitor