sheepfold vs pen

sheepfold and pen both are nouns.

Word	Noun	Adjective	Verb	Adverb
sheepfold	Yes	No	No	No
pen	Yes	No	Yes	No

As nouns, pen is a hypernym of sheepfold; that is, pen is a word with a broader meaning than sheepfold:

sheepfold (noun)	pen (noun)
a pen for sheep	female swan
	a writing implement with a point from which ink flows
	an enclosure for confining livestock
	a correctional institution for those convicted of major crimes
	a portable enclosure in which babies may be left to play

sheepfold (verb)	pen (verb)
	produce a literary work