A skeleton key (or a passkey) is known as one of the master key types of master key in which the serrated edge has been filed down in such a way that it can open numerous locks, and, in particular, the warded lock.

In a broader sense, it can be used as a master key to refer to any key, keycard or other device that can open a variety of locks.

In US English usage, 'skeleton key' also means a lever lock key. The term is sometimes considered to be the same as an antique key but it is actually not.

By the way, have you watched the movie 'The skeleton key'? Do you think such a title was suitable for it?

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