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 Britain most often refers to: * The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands * Great Britain, the largest island in the United King ...

, 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, the official residence of the British prime minister.

History

In early Gothic

ecclesiastical {{Short pages monitor