The Collaborative International Dictionary of English v.0.48:

Inveterate \In*vet"er*ate\, a. [L. inveteratus, p. p. of
   inveterare to render old; pref. in- in + vetus, veteris, old.
   See Veteran.]
   [1913 Webster]
   1. Old; long-established. [Obs.]
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            It is an inveterate and received opinion. --Bacon.
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   2. Firmly established by long continuance; obstinate;
      deep-rooted; of long standing; as, an inveterate disease;
      an inveterate abuse.
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            Heal the inveterate canker of one wound. --Shak.
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   3. Having habits fixed by long continuance; confirmed;
      habitual; as, an inveterate idler or smoker.
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   4. Malignant; virulent; spiteful. --H. Brooke.
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The Collaborative International Dictionary of English v.0.48:

Inveterate \In*vet"er*ate\, v. t.
   To fix and settle by long continuance. [Obs.] --Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inveterate
    adv 1: in a habitual and longstanding manner; "smoking
           chronically" [syn: chronically, inveterate]
    adj 1: habitual; "a chronic smoker" [syn: chronic,
           inveterate]