iceman vs murderer

iceman and murderer both are nouns.

Word	Noun	Adjective	Verb	Adverb
iceman	Yes	No	No	No
murderer	Yes	No	No	No

As nouns, murderer is a hypernym of iceman; that is, murderer is a word with a broader meaning than iceman:

iceman: a professional killer
murderer: a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)

Other hypernyms of iceman include liquidator, manslayer.

iceman (noun)	murderer (noun)
someone who cuts and delivers ice	a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)
a professional killer