Intercom (noun)

1. A system of telephones and loudspeakers for communication within a building or organization.
2. A small portable device for two-way communication over a short distance.

Origin:

A short form of intercommunication device, intercommunication is coined from the combination of inter- meaning between, and communication. it first appeared in the early 20th century.

Examples:

1. The intercom system in the building allows for easy communication between floors.
2. The intercom in the car allows the driver to communicate with passengers in the back seat.
3. The security guard used the intercom to warn the visitors about the closing of the building.
4. He used the intercom to call the receptionist.
5. The intercom is a great way to communicate with people in other rooms without having to go there.