boatswain vs gob

boatswain and gob both are nouns.

Word	Noun	Adjective	Verb	Adverb
boatswain	Yes	No	No	No
gob	Yes	No	No	No

As nouns, gob is a hypernym of boatswain; that is, gob is a word with a broader meaning than boatswain:

boatswain: a petty officer on a merchant ship who controls the work of other seamen
gob: a man who serves as a sailor

Other hypernyms of boatswain include Jack-tar, Jack, mariner, old salt, sea dog, seafarer, seaman, tar.

boatswain (noun)	gob (noun)
a petty officer on a merchant ship who controls the work of other seamen	informal terms for the mouth
	a lump of slimy stuff
	a man who serves as a sailor