The Rankine (°R) is an absolute unit of temperature, named after physicist William John Macquorn Rankine. It is related to the Fahrenheit temperature scale, just like the Kelvin scale is related to Celsius. Both the Kelvin and Rankine scale have zero values at absolute zero, but they are different at any values above this.
The Rankine scale is related to the Fahrenheit scale by the conversion:
In contrast, the Kelvin scale relates to the Celsius scale by the conversion: