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

Why it's important: Your SSN is a master key to your financial life.

From Salon

Fitzwater has also become a member of Crohn's and Colitis UK, who have given him a special card and a master key which allows him to access more than 9,000 locked public toilets.

From BBC

A maintenance worker gave police a master key to enter the apartment after nobody answered their knocks.

From Seattle Times

He is still struggling to master key strategic weapons, chiefly a spy satellite and a nuclear-armed submarine.

From BBC

Leidos told Congress in December it would install peepholes on dorm room doors, limit access to master keys that could open multiple bedrooms, and give teams in the field an extra satellite phone.

From Seattle Times