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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Advertisement The lawsuit alleges that the Los Angeles County Sheriff’s Department did not have access to the master key lock and no staff was present to open the door for deputies, which delayed the arrest of Nguyen. Ruben Vives, Los Angeles Times, 16 Oct. 2024 This woman recently accessed my apartment using a master key. Jeanne Phillips, The Mercury News, 22 Sep. 2024 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 See all Example Sentences for master key 

Word History

First Known Use

1577, in the meaning defined at sense 1

Time Traveler
The first known use of master key was in 1577

Dictionary Entries Near master key

Cite this Entry

“Master key.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/master%20key. Accessed 22 Nov. 2024.

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!