Spandrel

A spandrel, less often spandril or splaundrel, is the space between two arches or between an arch and a rectangular enclosure.

There are four or five accepted and cognate meanings of spandrel in architectural and art history, mostly relating to the space between a curved figure and a rectangular boundary - such as the space between the curve of an arch and a rectilinear bounding moulding, or the wallspace bounded by adjacent arches in an arcade and the stringcourse or moulding above them, or the space between the central medallion of a carpet and its rectangular corners, or the space between the circular face of a clock and the corners of the square revealed by its hood. Also included is the space under a flight of stairs, if it is not occupied by another flight of stairs. This is a common location to find storage space in residential structures.