Celsius definition
Thermometer on which the boiling point of water is 100 deg and the freezing point is 0 deg. The term replaces the word centigrade. To convert from Fahrenheit to Celsius, subtract 32 then multiply the result by 5 and divide by 9. To convert from Celsius to Fahrenheit, multiply by 9, then divide by 5. Now add 32 to the result.