passe-partout vs master key

passe-partout and master key both are nouns.

Word	Noun	Adjective	Verb	Adverb
passe-partout	Yes	No	No	No
master key	Yes	No	No	No

As nouns, passe-partout and master key are synonyms defined as:

Other synonyms of passe-partout include master, passkey.

passe-partout (noun)	master key (noun)
key that secures entrance everywhere	key that secures entrance everywhere
a mounting for a picture using gummed tape