lockkeeper vs skilled workman

lockkeeper and skilled workman both are nouns.

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

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

Other hypernyms of lockkeeper include skilled worker, trained worker.

lockkeeper (noun)	skilled workman (noun)
a worker in charge of a lock (on a canal)	a worker who has acquired special skills