Therm (heat)
Therm
Greek therme: heat; thermos: hot.
The hill town is famous for its warm thermal springs.
Thermometer
A tool that measures temperature.
The thermometer in Jaipur showed forty-four degrees in May.
Thermal
To do with heat; also warm clothing.
Diya packed thermal wear for the trip to Shimla.
Remember: Therm = heat + meter = measure. A thermostat keeps heat steady. Stress the second part: ther-MOM-i-ter, like 'speedometer' (spee-DOM-i-ter).