noun

1. purgation, esp. of the bowels
2. the purifying of the emotions or relieving of emotional tensions, esp. by art; concept applied originally by Aristotle to the effect of tragic drama on the audience
3. Psychiatry the alleviation of fear, problems, and complexes by bringing them to consciousness or giving them expression

Etymology: ModL < Gr katharsis, purification < kathairein, to purify < katharos, pure