1. [n]  someone who is physiologically dependent on a substance; abrupt deprivation of the substance produces withdrawal symptoms
2. [n]  someone who is so ardently devoted to something that it resembles an addiction; "a golf addict"; "a car nut"; "a control freak"
3. [v]  to cause (someone or oneself) to become dependent (on something, esp. a narcotic drug)

ADDICT is a 6 letter word that starts with A.

1. \Ad*dict"\, p. p.
   Addicted; devoted. [Obs.]
   

2. \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.
            He is addicted to his study.          --Beau. & Fl.
            That part of mankind that addict their minds to
            speculations.                         --Adventurer.
            His genius addicted him to the study of antiquity.
                                                  --Fuller.
            A man gross . . . and addicted to low company.
                                                  --Macaulay.
   2. To adapt; to make suitable; to fit. [Obs.]
            The land about is exceedingly addicted to wood, but
            the coldness of the place hinders the growth.
                                                  --Evelyn.
   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.