incumbent vs current

incumbent and current both are nouns.

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

incumbent (noun)	current (noun)
the official who holds an office	a steady flow of a fluid (usually from natural causes)
	dominant course (suggestive of running water) of successive events or ideas
	a flow of electricity through a conductor

incumbent (adjective)	current (adjective)
currently holding an office	occurring in or belonging to the present time
necessary (for someone) as a duty or responsibility; morally binding
lying or leaning on something else