gun for hire vs gunman

gun for hire and gunman both are nouns.

Word	Noun	Adjective	Verb	Adverb
gun for hire	Yes	No	No	No
gunman	Yes	No	No	No

As nouns, gun for hire and gunman are synonyms defined as:

Other synonyms of gun for hire include gun, gunslinger, hired gun, hit man, hitman, shooter, torpedo, triggerman.

gun for hire (noun)	gunman (noun)
a professional killer who uses a gun	a professional killer who uses a gun
	a person who shoots a gun (as regards their ability)