thermostat (ther•mo•stat)

1. an automatic device for regulating temperature by opening, or closing, the damper of a heating furnace, regulating supply of gas, or the like. Also for actuating fire or low temperature alarms, for controlling automatic sprinklers or fire doors, etc. Thermostats utilize either the differential expansion of solids, liquids, or gases subjected to heat or […]

vapor (vap•or)

1. diffused matter suspended in the air and impairing its transparency. 2. a substance in a gaseous state as distinguished from a liquid or solid state. 3. a gaseous substance that is at a temperature below its critical temperature and therefore liquifiable by pressure alone.