gunman vs liquidator

gunman and liquidator both are nouns.

Word	Noun	Adjective	Verb	Adverb
gunman	Yes	No	No	No
liquidator	Yes	No	No	No

As nouns, liquidator is a hypernym of gunman; that is, liquidator is a word with a broader meaning than gunman:

gunman: a professional killer who uses a gun
liquidator: a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)

Other hypernyms of gunman include manslayer, murderer.

gunman (noun)	liquidator (noun)
a professional killer who uses a gun	(law) a person (usually appointed by a court of law) who liquidates assets or preserves them for the benefit of affected parties
a person who shoots a gun (as regards their ability)	a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)