scheme arch vs diminished arch

scheme arch and diminished arch both are nouns.

Word	Noun	Adjective	Verb	Adverb
scheme arch	Yes	No	No	No
diminished arch	Yes	No	No	No

As nouns, scheme arch and diminished arch are synonyms defined as:

scheme arch and diminished arch: an arch whose height is less than half its width

Other synonyms of scheme arch include skeen arch, skene arch.

scheme arch (noun)	diminished arch (noun)
an arch whose height is less than half its width	an arch whose height is less than half its width