master key

English Thesaurus

1. key that secures entrance everywhere (noun.artifact)

hypernym	:	key,
definition	:	metal device shaped in such a way that when it is inserted into the appropriate lock the lock's mechanism can be rotated (noun.artifact)

hyponym	:	skeleton key,
definition	:	a passkey with much of the bit filed away so that it can open different locks (noun.artifact)