Catharsis refers to a sudden emotional breakdown, emotional release or climax that constitutes overwhelming feelings of great pity, sorrow, laughter, or any extreme change in emotion that results in the renewal, restoration and revitalization for living.
The catharsis view of aggression is that aggressive drive is reduced when one "releases" aggressive energy, either by acting aggressively or by fantasizing aggression.
Other /More definition:
Catharsis refers to emotional release; the release of psychic energy that is achieved by reliving traumatic events believed by Psychoanalysts to have important therapeutic benefits. Morever, Catharsis is the release of emotional tension/emotions and anxiety; rapid or sudden release of emotional tension thought to be an important factor in Psychoanalytic Therapy. It is defined as the spoken or written expression of strong negative emotion or anxiety, which may result in improvement in physiological or psychological health; the expression of emotions that is expected to lead to the reduction of disturbing symptoms. The Catharsis view of aggression is that aggressive drive is reduced when one "releases" aggressive energy, either by acting aggressively or by fantasizing aggression.