monitor

Display produced by a device that takes signals and displays them on a television screen or a computer monitor.

Any of various large tropical carnivorous lizards of Africa and Asia and Australia; fabled to warn of crocodiles.

Someone who supervises (an examination).

Someone who gives a warning so that a mistake can be avoided.

An ironclad vessel built by Federal forces to do battle with the Merrimac.

A piece of electronic equipment that keeps track of the operation of a system continuously and warns of trouble.

Electronic equipment that is used to check the quality or content of electronic transmissions.

Keep tabs on; keep an eye on; keep under surveillance.

“we are monitoring the air quality”

“the police monitor the suspect's moves”

Check, track, or observe by means of a receiver.