spandrel vs spandril

spandrel and spandril both are nouns.

Word	Noun	Adjective	Verb	Adverb
spandrel	Yes	No	No	No
spandril	Yes	No	No	No

As nouns, spandrel and spandril are synonyms defined as:

spandrel and spandril: an approximately triangular surface area between two adjacent arches and the horizontal plane above them

spandrel (noun)	spandril (noun)
an approximately triangular surface area between two adjacent arches and the horizontal plane above them	an approximately triangular surface area between two adjacent arches and the horizontal plane above them