Definition of Rankine (°R):
Older unit of absolute temperature. One degree (1°) rankine represents the same temperature difference as one degree on Fahrenheit scale, but the zero point of the scale is set at absolute zero. Thus, the rankine temperature is 459.67° plus the Fahrenheit temperature. One degree rankine is equal to five-ninth (0.55) of kelvin. Named after the Scottish engineer William Rankine (1820-70) who devised a cycle of operations in a heat engine (the Rankine Cycle).
As postpositive. Of a thermometric degree or specified number of degrees: measured on the Rankine scale.
Designating a scale of absolute temperature (i.e. one with its zero identified with absolute zero) in which the degrees are equal in size to those on the Fahrenheit scale; especially in Rankine scale.
Meaning of Rankine (°R) & Rankine (°R) Definition