The Collaborative International Dictionary of English v.0.48:

Addiction \Ad*dic"tion\, n. [Cf. L. addictio an adjudging.]
   The state of being addicted; devotion; inclination. "His
   addiction was to courses vain." --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

addiction
    n 1: being abnormally tolerant to and dependent on something
         that is psychologically or physically habit-forming
         (especially alcohol or narcotic drugs) [syn: addiction,
         dependence, dependance, dependency, habituation]
    2: an abnormally strong craving
    3: (Roman law) a formal award by a magistrate of a thing or
       person to another person (as the award of a debtor to his
       creditor); a surrender to a master; "under Roman law
       addiction was the justification for slavery"