superjacent vs incumbent

superjacent is not a noun while incumbent is a noun.

Word	Noun	Adjective	Verb	Adverb
superjacent	No	Yes	No	No
incumbent	Yes	Yes	No	No

superjacent (noun)	incumbent (noun)
	the official who holds an office

superjacent (adjective)	incumbent (adjective)
lying immediately above or on something else	currently holding an office
	necessary (for someone) as a duty or responsibility; morally binding
	lying or leaning on something else