master key

American  

noun

1. a key that will open a number of different locks, the proper keys of which are not interchangeable.

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master key British  

noun

1. Also called: pass key.  a key that opens all the locks of a set, the individual keys of which are not interchangeable

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Etymology

Origin of master key

First recorded in 1570–80

Example Sentences

At 15:19, she tried the door to the toilet, using a master key to unlock it.

From BBC

Staff had master keys that could unlock all the patients' rooms.

From BBC

"As we have said many times before, we have never built a backdoor or master key to any of our products or services and we never will."

From BBC

The company claims he sold a “master key” for $350 that facilitated cheating across a range of games.

From Los Angeles Times

"As we have said many times before, we have never built a backdoor or master key to any of our products or services and we never will," Apple says on its website.

From BBC