polemist vs author

polemist and author both are nouns.

Word	Noun	Adjective	Verb	Adverb
polemist	Yes	No	No	No
author	Yes	No	Yes	No

As nouns, author is a hypernym of polemist; that is, author is a word with a broader meaning than polemist:

polemist: a writer who argues in opposition to others (especially in theology)
author: writes (books or stories or articles or the like) professionally (for pay)

Other hypernyms of polemist include writer.

polemist (noun)	author (noun)
a writer who argues in opposition to others (especially in theology)	writes (books or stories or articles or the like) professionally (for pay)
	someone who originates or causes or initiates something

polemist (verb)	author (verb)
	be the author of