oceanaut vs skilled workman

oceanaut and skilled workman both are nouns.

Word	Noun	Adjective	Verb	Adverb
oceanaut	Yes	No	No	No
skilled workman	Yes	No	No	No

As nouns, skilled workman is a hypernym of oceanaut; that is, skilled workman is a word with a broader meaning than oceanaut:

oceanaut: a skilled worker who can live in underwater installations and participate in scientific research
skilled workman: a worker who has acquired special skills

Other hypernyms of oceanaut include skilled worker, trained worker.

oceanaut (noun)	skilled workman (noun)
a skilled worker who can live in underwater installations and participate in scientific research	a worker who has acquired special skills