The Collaborative International Dictionary of English v.0.48:

R'eaumur \R['e]`au`mur"\ (r[asl]`[=o]`m[.u]r"), a.
   Of or pertaining to Ren['e] Antoine Ferchault de R['e]aumur;
   conformed to the scale adopted by R['e]aumur in graduating
   the thermometer he invented. -- n. A R['e]aumur thermometer
   or scale.
   [1913 Webster]

   Note: The R['e]aumur thermometer is so graduated that 0[deg]
         marks the freezing point and 80[deg] the boiling point
         of water. Frequently indicated by R. Cf. Centigrade,
         and Fahrenheit. See Illust. of Thermometer.
         [1913 Webster]