upcast vs air passage

upcast and air passage both are nouns.

Word	Noun	Adjective	Verb	Adverb
upcast	Yes	No	No	No
air passage	Yes	No	No	No

As nouns, air passage is a hypernym of upcast; that is, air passage is a word with a broader meaning than upcast:

upcast: air passage consisting of a ventilation shaft through which air leaves a mine
air passage: a duct that provides ventilation (as in mines)

Other hypernyms of upcast include air duct, airway.

upcast (noun)	air passage (noun)
air passage consisting of a ventilation shaft through which air leaves a mine	a duct that provides ventilation (as in mines)