WordNet sense 1 (purging the body by the use of a cathartic to stimulate evacuation of the bowels):

catharsis, katharsis

WordNet sense 2 (a ceremonial cleansing from defilement or uncleanness by the performance of appropriate rites):

purification

WordNet sense 3 (the act of clearing yourself (or another) from some stigma or charge):

purge, purging