The Collaborative International Dictionary of English v.0.48:

Psychotherapy \Psy`cho*ther"a*py\, n. [Psycho- + therapy.]
   (Med.)
   Psychotherapeutics.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

psychotherapy
    n 1: the branch of psychiatry concerned with psychological
         methods [syn: psychotherapy, psychotherapeutics,
         mental hygiene]
    2: the treatment of mental or emotional problems by
       psychological means

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "psychotherapy":
   Arica movement, Erhard Seminars Training, New Consciousness,
   Pentothal interview, SAT, T-group, assertiveness training,
   behavior modification, behavior therapy, bioenergetics,
   biofeedback, confrontation therapy, conjoint therapy,
   consciousness raising, counseling, directive therapy,
   encounter therapy, est, family training, feminist therapy,
   gestalt therapy, group psychotherapy, group relations training,
   group sensitivity training, group therapy, healing arts,
   humanistic therapy, hypnoanalysis, hypnosis, hypnotherapy,
   hypnotism, marathon, marriage encounter, medical care,
   medical treatment, medication, medicines, mind cure, narcoanalysis,
   narcohypnosis, narcosynthesis, narcotherapy, nondirective therapy,
   occupational therapy, pastoral counseling, play therapy,
   primal therapy, prolonged narcosis, psychodrama,
   psychological counseling, psychosurgery, psychosynthesis,
   psychotherapeutics, radical therapy, rational-emotive therapy,
   reality therapy, recreational therapy, regression therapy,
   release therapy, scream therapy, sensitivity training,
   sensory awareness training, sleep treatment, supportive therapy,
   therapeusis, therapeutics, therapy, training group,
   transactional analysis, transcendental meditation,
   transpersonal therapy, treatment, vocational therapy