• noun:   any of various large tropical carnivorous lizards of Africa and Asia and Australia; fabled to warn of crocodiles
• noun:   a piece of electronic equipment that keeps track of the operation of a system continuously and warns of trouble
• noun:   electronic equipment that is used to check the quality or content of electronic transmissions
• noun:   display consisting of a device that takes signals from a computer and displays them on a CRT screen
• noun:   an iron-clad vessel built by Federal forces to do battle with the Merrimac
• noun:   someone who gives a warning so that a mistake can be avoided
• noun:   someone who supervises (an examination)
• verb:   keep tabs on; keep an eye on; keep under surveillance

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