upcast vs air duct

upcast and air duct both are nouns.

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

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

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

Other hypernyms of upcast include air passage, airway.

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