The word degree is equivalent to Latin gradus which, since the medieval period, could refer to any stage in a graded system of ranks or steps.
[1] The modern notation appears in print in the 1570s, with a borderline example by Jacques Pelletier du Mans in 1569, and was popularized by, among others, Tycho Brahe and Johannes Kepler, but didn't become universal.
Similarly, the introduction of the temperature scales with degrees in the 18th century was at first without such symbols, but with the word "gradus" spelled out.
Antoine Lavoisier in his "Opuscules physiques et chymiques" (1774) used the ordinal indicator with Arabic numerals – for example, when he wrote in the introduction: The 1o.
[2] The symbol is also declared as a notation for degrees of arc as early as 1831, in an American mathematics textbook for schools.
In the case of degrees of temperature, three scientific and engineering standards bodies (the International Bureau of Weights and Measures, the International Organization for Standardization and the U.S. Government Printing Office) prescribe printing temperatures with a space between the number and the degree symbol, e.g. 10 °C.
[4][5] However, in many works with professional typesetting, including scientific works published by the University of Chicago Press or Oxford University Press, the degree symbol is printed with no spaces between the number, the symbol, and the Latin letters "C" or "F" representing Celsius or Fahrenheit, respectively, e.g.