noun Someone who watches over something; a person in charge of something or someone.
The camp monitors look after the children during the night, when the teachers are asleep.
noun A device that detects and informs on the presence, quantity, etc., of something.
noun A device similar to a television set used as to give a graphical display of the output from a computer.
The information flashed up on the monitor.
noun A studio monitor or loudspeaker.
noun A program for viewing and editing.
a machine code monitor
noun The command line interface of an operating system.
noun A student leader in a class.
noun A relatively small armored warship with only one or two turrets (but often carrying unusually large guns for a warship of its size), usually designed for shore bombardment or riverine warfare rather than open-ocean combat. .mw-parser-output .defdate{font-size:smaller}