What is the meaning of "degree" of temperature? I see that there are four temperature scales, two of which start at absolute zero and who's values are referred to as "Kelvin" and "Rankine", and two others which do not start at absolute zero and who's values are referred to as "degrees Celsius" and "degrees Fahrenheit". What is the exact meaning of the word degree in this sense? Why is it used for two of the scales but not the other two? Is the reason because C and F do not start at absolute zero? Also, is the degree here the same degree as in angles? We say "the temperature is 20 degrees Celsius", but not "the length is 5 degrees meter". Furthermore, we say that "the angle is 45 degrees" without giving a unit (as if degree is the unit). Please enlighten me! Thanks!