In Aristotle, the cleansing (purifying, purging) of feelings such as pity and fear by feeling them in an aesthetic context, such as the theatre. The aim of tragedy is to achieve this purification. According to the younger Freud a psychological disorder could be relieved by a process of catharsis when the original traumatic event was re-enacted, although he later held that other repressive factors might inhibit this outcome.
Philosophy dictionary. Academic. 2011.