catharsis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Medicine Purgation, especially for the digestive system.
• noun A purifying or figurative cleansing of the emotions, especially pity and fear, described by Aristotle as an effect of tragic drama on its audience.
• noun A release of emotional tension, as after an overwhelming experience, that restores or refreshes the spirit.
• noun A technique used to relieve tension and anxiety by bringing repressed feelings and fears to consciousness.
• noun The therapeutic result of this process; abreaction.

from The Century Dictionary.

• noun In medicine, a natural or artificial purgation of any passage, especially the bowels. Also called apocatharsis.
• noun Used in English to express whatever Aristotle is supposed to have meant by the same word.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Med.) A natural or artificial purgation of any passage, as of the mouth, bowels, etc.
• noun (Psychotherapy) The process of relieving an abnormal excitement by reëstablishing the association of the emotion with the memory or idea of the event that first caused it, and of eliminating it by complete expression (called the abreaction).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun drama A release of emotional tension after an overwhelming vicarious experience, resulting in the purging or purification of the emotions, as through watching a dramatic production (especially a tragedy). Coined in this sense by Aristotle.
• noun Any release of emotional tension to the same effect, more widely.
• noun A purification or cleansing, especially emotional.
• noun psychology A therapeutic technique to relieve tension.
• noun medicine Purging of the digestive system.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun purging the body by the use of a cathartic to stimulate evacuation of the bowels
• noun (psychoanalysis) purging of emotional tensions