Catharsis - any emotional discharge which brings about a moral or spiritual renewal or welcome relief from tension and anxiety. The usual intent is for an audience to leave feeling this relief from tension or anxiety after having viewed a play.
The word comes from the Greek katharis, meaning “cleansing, or purification.” This evolved from kathairo, which means I cleanse, and katharos, which means “pure or clean.”
Catharsis was referred to by Aristotle (384 – 322 B.C.) in his Poetics:
Tragedy, then, is an imitation of an action that is serious, complete, and of a certain magnitude; . . . through pity and fear effecting the proper purgation of these emotions.
Book 6 : 2