controller

noun

1. One who controls something.
2. Any electric or mechanical device for controlling a circuit or system.
3. The chief accounting officer which audits, and manages the financial affairs of a company or government; a comptroller.
4. A mechanism that controls or regulates the operation of a machine, especially a peripheral device in a computer.
5. A hardware device designed to allow the user to play video games.
6. An iron block, usually bolted to a ship's deck, for controlling the running out of a chain cable. The links of the cable tend to drop into hollows in the block, and thus hold fast until disengaged.
7. The person who supervises and handles communication with an agent in the field.
8. The subject of a control verb. See Control (linguistics)
9. In software applications using the model-view-controller design pattern, the part or parts of the application that treat input and output, forming an interface between models and views.