c.1600, of habits, pursuits, etc., from L. addictionem (nom. addictio) "an awarding, a devoting," noun of action from addicere (see addict). Earliest sense was less severe: "inclination, penchant," but this has become obsolete. In main modern sense it is first attested 1906, in ref. to opium (there is an isolated instance from 1779, with ref. to tobacco).
A physical or psychological need for a habit-forming substance, such as a drug or alcohol. In physical addiction, the body adapts to the substance being used and gradually requires increased amounts to reproduce the effects originally produced by smaller doses. See more at withdrawal.
A habitual or compulsive involvement in an activity, such as gambling.