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a. Of or pertaining to René Antoine Ferchault de Réaumur; conformed to the scale adopted by Réaumur in graduating the thermometer he invented. -- n. A Réaumur thermometer or scale. [ 1913 Webster ]

☞ The Réaumur thermometer is so graduated that 0° marks the freezing point and 80° the boiling point of water. Frequently indicated by R. Cf. Centigrade, and Fahrenheit. See Illust. of Thermometer. [ 1913 Webster ]