excess vs supererogatory

excess is a noun but supererogatory is not a noun.

Word	Noun	Adjective	Verb	Adverb
excess	Yes	Yes	No	No
supererogatory	No	Yes	No	No

As adjectives, excess and supererogatory are synonyms defined as:

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

excess (noun)	supererogatory (noun)
excessive indulgence
immoderation as a consequence of going beyond sufficient or permitted limits
a quantity much larger than is needed
the state of being more than full

excess (adjective)	supererogatory (adjective)
more than is needed, desired, or required	more than is needed, desired, or required