under lock and key

• Audio (General Australian):

  (file)

under lock and key

1. (US, UK, idiomatic) imprisoned with little or no chance of escape; locked up.

   If it was him we can have him under lock and key in 24 hours.

2. (US, UK, idiomatic) safely guarded; locked away.
   • 2008, Edward J. McMillan, Model Policies and Procedures for Not-for-Profit Organizations, page 239:

     It is the policy of the organization to keep unused check supplies safeguarded under lock and key.