Refers to a device or mechanism that controls or maintains a certain level or amount of something, such as temperature or pressure.

Indicates an object that makes adjustments to fit certain specifications or requirements, often used in contexts like machinery or equipment.

Refers to a component that varies a signal or process to enhance operation, typically in communication and electronics contexts.

Describes a device or person that directs the operation of a system or process, ensuring everything functions according to set parameters.