Imagery (psychotherapy) is the use of mental images produced by the imagination as a form of psychotherapy. It can be classified by the modality of its content: visual, verbal, auditory, olfactory, tactile, gustatory, or kinesthetic. Common themes derive from nature imagery (e.g., forests and mountains), water imagery (e.g., brooks and oceans), travel imagery, etc. Imagery is used in the treatment of mental disorders and in helping patients cope with other diseases.
The terms guided imagery, directed reverie therapy, imagery and relaxation techniques are often synonymous; imagery is also in the class of relaxation technique. Imagery often forms a part of hypnosis, of autogenic therapy, of relaxation techniques, and of behavior therapy. 
- MeSH credits Encyclopedia of Human Behavior, vol. 4, pp29-30, 1994