\Span"drel\, n. [From {Span}.]
1. (Arch.) The irregular triangular space between the curve
   of an arch and the inclosing right angle; or the space
   between the outer moldings of two contiguous arches and a
   horizontal line above them, or another arch above and
   inclosing them.
2. A narrow mat or passe partout for a picture. [Cant]