1. A device that is used for checking the progress and operation of a system. A display and keyboard may be used in the roles of both a control console and a monitor. Display screens without keyboards may be used as remote monitors to allow the status of the system to be observed from remote locations.

2. Another name for supervisor, or even a complete operating system.

3. A programming construct devised by Hoare to allow controlled sharing of resources by otherwise asynchronous processes, and involving the provision of controlled passing of variables between the processes.