time lock

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A lock, as for a bank vault, containing a mechanism that prevents its being opened before a fixed time.

Century Dictionary and Cyclopedia

1. n. See lock.

Wiktionary

1. n. a lock, typically in on a door in a bank vault, that cannot be unlocked before a specified time

GNU Webster's 1913

1. n. a lock having clockwork attached, which, when wound up, prevents the bolt from being withdrawn when locked, until a certain interval of time has elapsed.