[1] : The Collaborative International Dictionary of English v.0.48

chronic \chron"ic\, a. l. chronicus, gr. ? concerning time,
   from ? time: cf. f. chronique.
   1. relating to time; according to time.
      1913 webster

   2. continuing for a long time; lingering; habitual.
      1913 webster

   chronic disease, one which is inveterate, of long
      continuance, or progresses slowly, in distinction from an
      acute disease, which speedly terminates.
      1913 webster
see also:
chronic disease 

[2] : WordNet (r) 2.0

chronic
     adj 1: being long-lasting and recurrent or characterized by long
            suffering; "chronic indigestion"; "a chronic shortage
            of funds"; "a chronic invalid" ant: acute
     2: having a habit of long standing; "a chronic smoker" syn: confirmed,
         habitual, inveteratea
see also:
acute confirmed habitual inveteratea 

[3] : Moby Thesaurus II by Grady Ward, 1.0

73 moby thesaurus words for "chronic":
   abiding, accepted, accustomed, age-long, aged, ancient, antique,
   confirmed, constant, continuing, customary, deep-dyed, deep-fixed,
   deep-rooted, deep-seated, deep-set, deep-settled, diuturnal,
   durable, dyed-in-the-wool, enduring, established, evergreen, fast,
   fixed, habitual, habituated, hardened, hardy, immutable, implanted,
   incorrigible, inculcated, infixed, ingrained, instilled,
   intransient, inveterate, irreversible, lasting, lingering,
   long-established, long-lasting, long-lived, long-standing,
   long-term, longeval, longevous, macrobiotic, of long duration,
   of long standing, perdurable, perduring, perennial, permanent,
   perpetual, persistent, persisting, remaining, rooted, routine,
   sempervirent, set, settled, settled in habit, stable, staying,
   steadfast, thorough, tough, unfading, vital, wonted

Chronic >> C Words
Chronic, definition of term: Chronic
chronic_pag1.html

Chronic Disease >> C Words
Chronic Disease, definition of term: Chronic Disease
chronic+disease_pag1.html