Under lock and key Meaning in English
expression
Definition
Kept in a very safe or secure place, usually locked so others cannot get it. Often used for valuable or important items or to describe someone who is locked away.
Usage & Nuances
An idiom, not literal. Applies to both objects (like valuables) and people (e.g., prisoners). Often heard in formal or descriptive contexts, not slang. Common with verbs like 'keep', 'put', and 'hold'.
Example Sentences
The crown jewels are kept under lock and key.
basic
Important documents are stored under lock and key.
basic
The prisoner was kept under lock and key at night.
basic
My dad keeps his private letters under lock and key so no one can read them.
natural
If you lend me your camera, I promise I'll keep it under lock and key.
natural
After the break-in, we started keeping valuables under lock and key.
natural