An ordinary-looking object with a hidden space for carrying or storing things.
The CIA glossary uses the term concealment device. One example is the hollow nickel whose discovery the FBI describes in the Abel case.1,2
The Crypto Museum distinguishes an active concealment – an object that still performs its function, such as a watch with a hidden compartment – from a passive one, which serves only to hide things.3
Sources
- CIA, Spy Speak Glossary
- FBI, A Byte Out of History: The Case of the Hollow Nickel (2004)
- Crypto Museum, Glossary of covert expressions
Checked: 4 November 2026