skeleton key

American  

noun

1. a key with nearly the whole substance of the bit filed away so that it may open various locks.

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skeleton key British  

noun

1. Also called: passkey.  a key with the serrated edge filed down so that it can open numerous locks

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Etymology

Origin of skeleton key

First recorded in 1800–10

Example Sentences

“Megadoc” is not exactly a skeleton key for understanding “Megalopolis,” but it is useful and insightful, full of scenes of conflict followed by resolution, understanding emerging from confusion.

From Los Angeles Times

The skeleton key to understanding reactionary conservatism is quite simple: they are scared, all the time, of everything.

From Salon

Introducing the 688-page biography this way seems designed to address Musk’s recent turn towards combativeness and cruelty — if not justifying it, then offering a skeleton key to understanding where it’s rooted.

From Los Angeles Times

“Microsoft should not have had a single skeleton key that, when inevitably stolen, could be used to forge access to different customers’ private communications.”

From Seattle Times

Those looking for a felt skeleton key to unlock his various idiosyncrasies aren’t likely to find one.

From New York Times