The Réaumur is a unit of temperature named for René Antoine Ferchault de Réaumur (1683-1757), who first proposed it in 1731. The freezing point of water is 0 deg. Reaumur, the boiling point 80 deg. Reaumur. Hence a degree Reaumur is 1.25 degrees Celsius or Kelvin.
The Reaumur scale is still used in some parts of Europe, but today it is in most places of mainly historical significance.