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1610s, of medicines, from Latin catharticus, from Greek kathartikos "fit for cleansing, purgative," from katharsis "purging, cleansing" (see catharsis). General sense is from 1670s. Related: Cathartical.
cathartic ca·thar·tic (kə-thär'tĭk)
Inducing catharsis; purgative. n.
An agent for purging the bowels, especially a laxative.