incumbency vs term of office

incumbency and term of office both are nouns.

Word	Noun	Adjective	Verb	Adverb
incumbency	Yes	No	No	No
term of office	Yes	No	No	No

As nouns, incumbency and term of office are synonyms defined as:

incumbency and term of office: the term during which some position is held

Other synonyms of incumbency include tenure.

incumbency (noun)	term of office (noun)
the office of an incumbent	the term during which some position is held
a duty that is incumbent upon you
the term during which some position is held