master key

noun

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

master key

noun

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

Word History and Origins

Origin of master key¹

First recorded in 1570–80

Example Sentences

There are methods and formulae in science which serve as master keys to many apparently different...

From Quanta Magazine

You must search for the secret springs that govern his actions and for the master key that will unlock his heart.

From Project Gutenberg

Not since he had discovered the master-key of Evolution had Thyrsis come upon any set of ideas that meant so much to him.

From Project Gutenberg

The theory of the class struggle is the master key to the bewilderments and confusions of history.

From Project Gutenberg

This was the master-key to her behaviour, and once I had got it, which I soon did, it was easy to unlock her breast.

From Project Gutenberg

Look, only look into the closet; wait here a moment, and I'll fetch a master key that shall open every one of them.

From Project Gutenberg