An electrical switch, in a generator or motor, that periodically reverses the direction of an electric current.
A binary map in a given group G, given by [g, h] = ghg⁻¹h⁻¹, where g and h are elements of G, which yields the group's identity if and only if the group operation commutes for g and h.
A binary map in a given ring R, given by [a, b] = ab − ba, where a and b are elements of R, which yields the ring's zero element if and only if the multiplication operation commutes for a and b.
Any electric or mechanical device for controlling a circuit or system.
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 chief accounting officer which audits, and manages the financial affairs of a company or government; a comptroller.
One who controls something.
The person who supervises and handles communication with an agent in the field.
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.
A hardware device designed to allow the user to play video games.
A mechanism that controls or regulates the operation of a machine, especially a peripheral device in a computer.
The subject of a control verb. See Control (linguistics)