The Collaborative International Dictionary of English v.0.48:

chiropractic \chiropractic\ n.
   a method of medical treatment that manipulates body
   structures, especially the spine, in the belief that it
   restores proper nerve functioning.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

chiropractic
    n 1: a method of treatment that manipulates body structures
         (especially the spine) to relieve low back pain or even
         headache or high blood pressure

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "chiropractic":
   Galenic medicine, allopathic, allopathy, ayurveda, chiropodic,
   chiropraxis, clinical, dental, eclecticism, exodontic, homeopathic,
   homeopathy, hydropathic, iatric, medical, naturopathic,
   neurological, obstetric, orthodontic, orthopedic, osteopathic,
   osteopathy, pediatric, periodontic, prosthodontic, surgical