A Dormer Window is a window projecting vertically from a sloping roof, providing additional headroom, natural light and ventilation within attic or upper-storey rooms. Dormer windows became increasingly popular during the Georgian, Victorian and Edwardian periods and are recognised by their pitched, hipped or flat roofs, often enhanced with decorative mouldings and architectural detailing. *Related Terms*\ Architectural Antiques, Gable, Rooflight, Sash Window, Window.