oriolum

Medieval Latin oriolum named a type of gallery or porch — the etymology is genuinely disputed. Possible sources include Latin aurea (golden, perhaps for the quality of light), area (an open courtyard), or a connection to Old French oriol (a gallery or porch). By the 14th century in English, an oriel specifically named a projecting bay window supported on corbels or brackets — a window that extended the room's floor space outward.

Oriel windows were characteristic of the late medieval and Tudor architecture of England and France. Oxford colleges are famous for their oriels: the oriel in Oriel College's Front Quad (which gives the college its name), the bay windows of Christ Church Hall, the protruding windows of Brasenose and Exeter. The oriel allowed more light into a room while the wall below remained solid, and provided an elevated view down the street or across the courtyard.

The oriel window was a status marker in domestic architecture. A house with an oriel projected its owner's wealth into the street — literally, since the bay window pushed the room outward, claiming extra space above the public way. Tudor merchants built oriels on their town houses. The elaborate oriels on the Shambles in York, where butchers' shops projected their display windows over the narrow street, were commercial oriels.

Today oriels survive in historic buildings and are occasionally reproduced in new construction as heritage references. The bay window in 20th-century suburban housing is a simplified version — sitting on the ground rather than corbelled from the wall, but preserving the outward projection that gives extra light and space.