/ ˈθɜːməstæt; NAmE ˈθɜːrm-/ noun
a device that measures and controls the temperature of a machine or room, by switching the heating or cooling system on and off as necessary
► thermo·stat·ic / ˌθɜːməˈstætɪk; NAmE ˌθɜːrm-/ adjective [ only before noun ]
► thermo·stat·ic·al·ly / -kli; NAmE / adverb
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WORD ORIGIN
mid 19th cent.: from thermo- of heat + -stat .