privateersman vs crewman

privateersman and crewman both are nouns.

Word	Noun	Adjective	Verb	Adverb
privateersman	Yes	No	No	No
crewman	Yes	No	No	No

As nouns, crewman is a hypernym of privateersman; that is, crewman is a word with a broader meaning than privateersman:

Other hypernyms of privateersman include crew member, officer, ship's officer.

privateersman (noun)	crewman (noun)
an officer or crew member of a privateer	a member of a work crew
	a member of a flight crew
	any member of a ship's crew