ETYM Latin, from monere. Related to Monition, Mentor.
Provides a quantitative measurement, not qualitative. It measures continuously a condition that must be kept within prescribed limits. It does not differentiate between compounds.
1. A piece of electronic equipment that keeps track of the operation of a system continuously and warns of trouble.
2. Equipment that is used to check the quality or content of electronic transmissions.

Any of various large tropical carnivorous lizards of Africa Asia and Australia; fabled to warn of crocodiles; SYN. monitor lizard, varan.
Any of various lizards of the family Varanidae, found in Africa, S Asia, and Australasia. Monitors are generally large and carnivorous, with well-developed legs and claws and a long powerful tail that can be swung in defense.
Monitors include the Komodo dragon, the largest of all lizards, and also the slimmer Salvador’s monitor Varanus salvadorii, which may reach 2.5 m/8 ft. Several other monitors, such as the lace monitor V. varius, the perentie V. giganteus of Australia, and the Nile monitor V. niloticus of Africa, are up to 2 m/6 ft long.

The device on which images generated by the computer’s video adapter are displayed. The term monitor usually refers to a video display and its housing. The monitor is attached to the video adapter by a cable. See also CRT.
Alternative term for a display screen.
A device that takes signals from a computer and displays them on a CRT screen.

To keep tabs on; keep an eye on; keep under surveillance; SYN. supervise, ride herd on.