pendragon vs headman

pendragon and headman both are nouns.

Word	Noun	Adjective	Verb	Adverb
pendragon	Yes	No	No	No
headman	Yes	No	No	No

As nouns, headman is a hypernym of pendragon; that is, headman is a word with a broader meaning than pendragon:

Other hypernyms of pendragon include chief, chieftain, tribal chief.

pendragon (noun)	headman (noun)
the supreme war chief of the ancient Britons	the head of a tribe or clan
	an executioner who beheads the condemned person