thoroughfare vs impasse

thoroughfare and impasse both are nouns.

Word	Noun	Adjective	Verb	Adverb
thoroughfare	Yes	No	No	No
impasse	Yes	No	No	No

As nouns, impasse is a hyponym of thoroughfare; that is, impasse is a word with a more specific, narrower meaning than thoroughfare:

Other hyponyms of thoroughfare include artery, blind alley, cul de sac, dead-end street, street, street.

thoroughfare (noun)	impasse (noun)
a public road from one place to another	a street with only one way in or out
	a situation in which no progress can be made or no advancement is possible