In espionage, a cut-out is a courier or mechanism used to pass information and devices from one spy to another while operating in a "denied area" or a hostile environment.
The two forms of cut-outs are the block and chain. A block cut-out is an agent familiar with the entire spy network or cell and those who are in it, while the chain cutout is simply an agent who is aware of only the person providing the information and the spy who is receiving the information. The chain cut-out helps to maintain the compartmentalization of the spy network, which increases security by maintaining everyone's anonymity.
The term cut-out may also be used more generally to describe a person or agency used as a pawn by intelligence agencies.