The Collaborative International Dictionary of English v.0.48:

Addict \Ad*dict"\, p. p.
   Addicted; devoted. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Addict \Ad*dict"\, v. t. [imp. & p. p. Addicted; p. pr. & vb.
   n. Addicting.] [L. addictus, p. p. of addicere to adjudge,
   devote; ad + dicere to say. See Diction.]
   1. To apply habitually; to devote; to habituate; -- with to.
      "They addict themselves to the civil law." --Evelyn.
      [1913 Webster]

            He is addicted to his study.          --Beau. & Fl.
      [1913 Webster]

            That part of mankind that addict their minds to
            speculations.                         --Adventurer.
      [1913 Webster]

            His genius addicted him to the study of antiquity.
                                                  --Fuller.
      [1913 Webster]

            A man gross . . . and addicted to low company.
                                                  --Macaulay.
      [1913 Webster]

   2. To adapt; to make suitable; to fit. [Obs.]
      [1913 Webster]

            The land about is exceedingly addicted to wood, but
            the coldness of the place hinders the growth.
                                                  --Evelyn.
      [1913 Webster]

   Syn: Addict, Devote, Consecrate, Dedicate. Addict was
        formerly used in a good sense; as, addicted to letters;
        but is now mostly employed in a bad sense or an
        indifferent one; as, addicted to vice; addicted to
        sensual indulgence. "Addicted to staying at home." --J.
        S. Mill. Devote is always taken in a good sense,
        expressing habitual earnestness in the pursuit of some
        favorite object; as, devoted to science. Consecrate and
        dedicate express devotion of a higher kind, involving
        religious sentiment; as, consecrated to the service of
        the church; dedicated to God.
        [1913 Webster]

WordNet (r) 3.0 (2006):

addict
    n 1: someone who is so ardently devoted to something that it
         resembles an addiction; "a golf addict"; "a car nut"; "a
         bodybuilding freak"; "a news junkie" [syn: addict, nut,
         freak, junkie, junky]
    2: someone who is physiologically dependent on a substance;
       abrupt deprivation of the substance produces withdrawal
       symptoms
    v 1: to cause (someone or oneself) to become dependent (on
         something, especially a narcotic drug) [syn: addict,
         hook]

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "addict":
   LSD user, acidhead, address, adherent, adjust, admirer, aficionado,
   alcoholic, apply, aspirant, aspirer, bias, buff, bug, candidate,
   chain smoker, cocaine sniffer, cokie, collector, coveter, cubehead,
   demon, desirer, devotee, dipsomaniac, direct, dispose, dope fiend,
   doper, drug abuser, drug addict, drug user, drunkard, eager beaver,
   energumen, enthusiast, faddist, fan, fanatic, fancier, fiend,
   follower, freak, glue sniffer, great one for, groupie, habitual,
   habitue, hankerer, head, heavy smoker, hobbyist, hopeful, hophead,
   hound, hype, incline, infatuate, junkie, lover, marijuana smoker,
   methhead, narcotics addict, nut, pillhead, pothead, predispose,
   pursuer, putterer, rhapsodist, snowbird, solicitant, speed freak,
   sucker for, suitor, supporter, take to, tripper, user, visionary,
   votary, wanter, wisher, yearner, zealot