Spandrel or Spandril

span·drel
–noun

1. Architecture. an area between the extradoses of two adjoining arches, or between the extrados of an arch and a perpendicular through the extrados at the springing line.

2. (in a steel-framed building) a panellike area between the head of a window on one level and the sill of a window immediately above.

3. Philately. the decoration occupying the space at the corner of a stamp between the border and an oval or circular central design.

Also, spandril.

[Origin: 1470–80; earlier spaundrell]