tunnel vs penetrate

tunnel is a noun but penetrate is not a noun.

Word	Noun	Adjective	Verb	Adverb
tunnel	Yes	No	Yes	No
penetrate	No	No	Yes	No

As verbs, penetrate is a hypernym of tunnel; that is, penetrate is a word with a broader meaning than tunnel:

Other hypernyms of tunnel include perforate.

tunnel (noun)	penetrate (noun)
a passageway through or under something, usually underground (especially one for trains or cars)
a hole made by an animal, usually for shelter

tunnel (verb)	penetrate (verb)
force a way through	come to understand
move through by or as by digging	become clear or enter one's consciousness or emotions
	pass into or through, often by overcoming resistance
	insert the penis into the vagina or anus of
	spread or diffuse through
	make one's way deeper into or through
	enter a group or organization in order to spy on the members