footnote vs pen

footnote and pen both are nouns.

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

As verbs, pen is a hypernym of footnote; that is, pen is a word with a broader meaning than footnote:

Other hypernyms of footnote include compose, indite, write.

footnote (noun)	pen (noun)
a printed note placed below the text on a printed page	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

footnote (verb)	pen (verb)
add explanatory notes to or supply with critical comments	produce a literary work