Real Dictionary

thermostat
countable noun: A thermostat is a device that switches a system or motor on or off according to the temperature. Thermostats are used, for example, in central heating systems and fridges.

thermostat in American English
an apparatus for regulating temperature, esp. one that automatically controls a heating or cooling unit
noun: a device, including a relay actuated by thermal conduction or convection, that functions to establish and maintain a desired temperature automatically or signals a change in temperature for manual adjustment
transitive verb: to equip or control with a thermostat

thermostat in British English
noun: a device that maintains a system at a constant temperature. It often consists of a bimetallic strip that bends as it expands and contracts with temperature, thus breaking and making contact with an electrical power supply

thermostat in Electrical Engineering
noun: A thermostat is a type of circuit that shows whether a measured temperature is above or below a particular point, and is used for thermal protection and simple temperature control systems.