kelvin (formerly degree kelvin)

Definition: Symbol K. The SI unit of thermodynamic temperature equal to the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The magnitude of the Kelvin is equal to that of the degree Celsius but a temperature expressed in degrees Celsius is numerically equal to the temperature in kelvins minus 273.15. The absolute zero of temperature has a temperature 0 K (-273.15°C). The former name degree kelvin became obsolete by international agreement in 1967 and the degree symbol (^o) is no longer used.