'addiction' definitions:

Definition of 'addiction'

From: WordNet
noun
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]
noun
An abnormally strong craving
noun
(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"

Synonyms of 'addiction'

From: Moby Thesaurus