superfluous vs supernumerary

superfluous is not a noun while supernumerary is a noun.

Word	Noun	Adjective	Verb	Adverb
superfluous	No	Yes	No	No
supernumerary	Yes	Yes	No	No

As adjectives, superfluous and supernumerary are synonyms defined as:

superfluous and supernumerary: more than is needed, desired, or required

Other synonyms of superfluous include excess, extra, redundant, spare, supererogatory, surplus.

superfluous (noun)	supernumerary (noun)
	a minor actor in crowd scenes
	a person serving no apparent function

superfluous (adjective)	supernumerary (adjective)
more than is needed, desired, or required	more than is needed, desired, or required
serving no useful purpose; having no excuse for being