The Collaborative International Dictionary of English v.0.48:

Therapeutic \Ther`a*peu"tic\, Therapeutical \Ther`a*peu"tic*al\,
   a. [F. th['e]rapeutique, Gr. ?, from ? attendant, servant, ?
   to serve, take care of, treat medically, ? attendant,
   servant.] (Med.)
   Of or pertaining to the healing art; concerned in discovering
   and applying remedies for diseases; curative. "Therapeutic or
   curative physic." --Sir T. Browne.
   [1913 Webster]

         Medicine is justly distributed into "prophylactic," or
         the art of preserving health, and therapeutic, or the
         art of restoring it.                     --I. Watts.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Therapeutic \Ther`a*peu"tic\, n.
   One of the Therapeutae.
   [1913 Webster]

WordNet (r) 3.0 (2006):

therapeutic
    adj 1: tending to cure or restore to health; "curative powers of
           herbal remedies"; "her gentle healing hand"; "remedial
           surgery"; "a sanative environment of mountains and fresh
           air"; "a therapeutic agent"; "therapeutic diets" [syn:
           curative, healing(p), alterative, remedial,
           sanative, therapeutic]
    2: relating to or involved in therapy; "therapeutic approach to
       criminality" [syn: therapeutic, therapeutical]
    n 1: a medicine or therapy that cures disease or relieve pain
         [syn: remedy, curative, cure, therapeutic]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "therapeutic":
   adjuvant, aidful, alterative, analeptic, beneficial, conducive,
   constructive, contributory, corrective, curative, furthersome,
   good for, healing, healthy, helpful, iatric, medical, medicative,
   medicinal, positive, profitable, remedial, restorative, salubrious,
   salutary, sanative, sanatory, serviceable, theriac, useful