controller

noun

• One who controls something.
• Any electric or mechanical device for controlling a circuit or system.
• A person who audits, and manages the financial affairs of a company or government; a comptroller.
• A mechanism that controls or regulates the operation of a machine, especially a peripheral device in a computer.
• 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.
• The person who supervises and handles communication with an agent in the field.
• The subject of a control verb. See Control (linguistics)
• 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.