harbinger vs annunciate

harbinger is a noun but annunciate is not a noun.

Word	Noun	Adjective	Verb	Adverb
harbinger	Yes	No	Yes	No
annunciate	No	No	Yes	No

As verbs, harbinger and annunciate are synonyms defined as:

Other synonyms of harbinger include announce, foretell, herald.

harbinger (noun)	annunciate (noun)
something that precedes and indicates the approach of something or someone

harbinger (verb)	annunciate (verb)
foreshadow or presage	foreshadow or presage