Closed-circuit (adjective)

1. Designating or of a system or network in which the signal or image is transmitted over a restricted range of stations or receivers.
2. Designating or of a system or network that is not connected to the general public or other external systems.

Origin:

Composed of two words "closed" meaning shut or sealed and "circuit" meaning a complete route or loop of electrical current.

Examples:

1. The police were able to monitor the situation through a closed-circuit television camera.
2. The security system is based on closed-circuit cameras that monitor the entire building.
3. The closed-circuit system enables the teacher to control what the students see on their screens.
4. The closed-circuit system is only for internal use and not connected to the internet.
5. The closed-circuit network is designed for secure communication between the company's different departments.