skeleton key vs passkey

skeleton key and passkey both are nouns.

Word	Noun	Adjective	Verb	Adverb
skeleton key	Yes	No	No	No
passkey	Yes	No	No	No

As nouns, passkey is a hypernym of skeleton key; that is, passkey is a word with a broader meaning than skeleton key:

skeleton key: a passkey with much of the bit filed away so that it can open different locks
passkey: key that secures entrance everywhere

Other hypernyms of skeleton key include master, master key, passe-partout.

skeleton key (noun)	passkey (noun)
a passkey with much of the bit filed away so that it can open different locks	key that secures entrance everywhere