master key

noun

plural master keys

1

a

: a key designed to open any of a set of similar locks (as on the doors of a building)

The porter unlocked the door with his master key.

—Paul Wilkinson

… he borrowed the electronic master key …—a fob which unlocks all the bedrooms in the building—and used it to enter another resident's room.

—Jason Evans

… the … idea of coordinating luggage inspection by providing locks that the TSA can open with a master key.

—Ryan Davis

called also passkey

b

: something (such as a set of computer instructions or a specific sequence of characters) that provides digital access to a variety of systems, files, etc.

… an alarmingly powerful cipher … that could be used as a master key to bypass basically any security system imaginable …

—Sara Netzley

The cybercriminals behind the … ransomware have decided to close up shop and have now released the master key capable of decrypting files locked with their malware.

—Anthony Spadafora

You can store all your passwords in one database, which is locked with a master key. So you only have to remember one single master key to unlock the whole database.

—TechSpot.com

2

: a crucial means of understanding or attaining something

—usually used with to

That's when it clicked. I had trained my mind to think what I wanted. At that point, I knew mindset training was the master key to success.

—David DeRam

One approach to defeating aging suggests replacing body parts as they fail. Another aims at finding a master key to youth.

—Todd Friend

… a man I thought might hold the master key to one of the strangest scholarly mysteries in recent decades …

—Ariel Sabar

Examples of master key in a Sentence

Recent Examples on the Web

No matter how luxurious a hotel is, the realities are unavoidable: locks break, there are master key cards, and break-ins happen. —Jillian Dara, Travel + Leisure, 11 Aug. 2024

The robber makes a copy of the master key, which provides access to all of the landlord's buildings and apartments. —Renee Dudley, ProPublica, 13 June 2024

According to court documents, Coleman and Dixon looked for USPS mail carriers through Dallas-Fort Worth to obtain an arrow key, a master key used by USPS employees to collect mail deposited in blue USPS collection boxes. —Nicole Lopez, Fort Worth Star-Telegram, 2 July 2024

The robber unlocks the office safe, which contains a master key. —Renee Dudley, ProPublica, 13 June 2024

Word History

First Known Use

1577, in the meaning defined at sense 1