The Collaborative International Dictionary of English v.0.48:

Kelvin \Kel"vin\ (k[e^]l"v[i^]n), n. [from Lord Kelvin, English
   physicist.]
   The SI unit of temperature, defined as being 1/273.16 of the
   triple point of water; abbreviated K. The melting point of
   water at 760 mm pressure is 273.15 Kelvins, and the boiling
   point 373.15 Kelvins. One degree Kelvin is equal to one
   degree Centigrade, and 9/5 degrees Fahrenheit.
   [PJC]

WordNet (r) 3.0 (2006):

kelvin
    n 1: the basic unit of thermodynamic temperature adopted under
         the Systeme International d'Unites [syn: kelvin, K]
    2: British physicist who invented the Kelvin scale of
       temperature and pioneered undersea telegraphy (1824-1907)
       [syn: Kelvin, First Baron Kelvin, William Thompson]