The Collaborative International Dictionary of English v.0.48:

joule \joule\ (j[=oo]l), n. [From the distinguished English
   physicist, James Prescott Joule (1818-1889).] (Physics.)
   A unit of work which is equal to 10^7 ergs (the unit of
   work in the C. G. S. system of units), and is equivalent to
   one watt-second, the energy expended in one second by an
   electric current of one ampere in a resistance of one ohm;
   also called the absolute joule. It is abbreviated J or j.
   The international joule is slightly larger, being 1.000167
   times the absolute joule. The absolute joule is approximately
   equal to 0.737562 foot pounds, 0.239006 gram-calories (small
   calories), and 3.72506 x 10^-7 horsepower-hours, and
   0.000948451 B.t.u. --HCP61
   [1913 Webster +PJC]

   Joule's equivalent. See under Equivalent, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

joule
    n 1: a unit of electrical energy equal to the work done when a
         current of one ampere passes through a resistance of one
         ohm for one second [syn: joule, J, watt second]
    2: English physicist who established the mechanical theory of
       heat and discovered the first law of thermodynamics
       (1818-1889) [syn: Joule, James Prescott Joule]