I couldn't find any information on therometer.
If you meant thermometer, that's an instrument to measure temperature.
use of therometer?
Thermometers are used to see if you have a fever or tell you how cold it is outside. Made up of thermo (heat) and meter (measuring device), the meaning of the wordthermometer is pretty straightforward. Thermometers measure temperatures in degrees, according to either the Celsius or Fahrenheit system.
thermometer - Dictionary Definition : Vocabulary.com