spandrel

noun6

1. •
   The space (often more or less triangular) between the outer curve of an arch (the extrados) and a straight-sided figure that bounds it; the space between two contiguous arches and a straight feature above them.
2. •
   The triangular space under a stair; the material that fills the space.
3. •
   A phenotypic characteristic that evolved as a side effect of an adaptation in response to evolutionary pressure.
4. •
   Horizontal member between the windows of successive storeys of a tall building.

   • Due to the fact that the walls are joined by floors and spandrels, a coupling effect is produced. Depending on the extent of the spandrels, this coupling effect will be bigger or smaller. — 2002
5. •
   An oriental rug having a pattern of arches; the design in the corners of such a rug, especially in a prayer rug.
6. •
   (Philippines) soffit (usually used to describe metal or corrugated plastic types of roof soffit)