A unit of temperature formerly used in continental Europe. The Réaumur temperature scale is named for the French scientist René-Antoine Ferchault de Réaumur (1683-1757). It is similar to the Celsius scale in having its zero point at the freezing temperature of water, but the interval between the freezing and boiling temperatures of water equals 80 °r instead of 100 °C. Therefore, 1 °r equals 1.25 °C or 2.25 °F