What unit of measurement is Celsius also known as?

• A. Fahrenheit
• B. Kelvin
• C. Centigrade
• D. Reaumur

Answer: (C)

The unit of measurement Celsius is also known as Centigrade. This name comes from the scale's original definition, which divided the temperature range between the freezing point of water (0 degrees) and the boiling point of water (100 degrees) into 100 equal parts. The term "Centigrade" literally means "consisting of 100 degrees" (from the Latin "centum" meaning hundred and "gradus" meaning steps or degrees).

In scientific contexts, the name Celsius is often preferred over Centigrade, but both refer to the same temperature measurement system. This dual naming can be traced back to historical usage, while "Celsius" honors the Swedish astronomer Anders Celsius, who developed the temperature scale in the 18th century.

The other terms listed—Fahrenheit, Kelvin, and Reaumur—refer to different temperature scales and are not synonymous with Celsius. Fahrenheit is primarily used in the United States, Kelvin is the SI unit of temperature used in scientific contexts, and Reaumur is an older scale that is not widely used today.