The English word 'catharsis' is a transliteration of the ancient Greek noun κάθαρσις‚ (katharsis), which means: purification or cleansing. The word katharsis was used in a religious context of the cleansing of an individual from guilt or sin, and in a medical context of the cleansing of the body of harmful or unwanted substances. It was also famously used by the philosopher Aristotle in his definition of tragedy (see further Catharsis in Aristotle's definition of tragedy). There was a related verb καθαρίζειν (katharizein, to cleanse, purify, or purge) and a related adjective καθαρός‚ (katharos, pure), which is the origin of the girl's name Catherine (alternatively spelt Katharine, Kathryn, etc.) and of the word Cathar (i.e., a member of the heretical Christian sect which flourished in Provence in the twelfth and thirteenth centuries).
The English word 'catharsis' is used in a number of different contexts - in psychology and psychotherapy, where it refers to the bringing into full consciousness of repressed thoughts, desires, and experiences and the consequent relief of tension in the patient; in medical contexts, where it means: the purging or cleansing of the body, and especially the bowels, of harmful or unwanted substances; and in literary criticism, particularly in the discussion of tragedy and Aristotle's theory of catharsis (see further Catharsis in Aristotle's definition of tragedy). The word may also be used more generally outside these contexts, in a way analogous to its use in psychology or psychiatry, to refer to an event or occasion such as an outburst of angry emotion or an uninhibited exchange of views which by bringing into the open what had previously been unacknowledged serves, e.g., to remove tensions in a relationship or to improve the atmosphere in a meeting. The adjective from 'catharsis' is 'cathartic', which may be used to describe any substance, process, or event which brings about a catharsis. The word 'cathartic' is also sometimes used as a noun - a cathartic is usually a purgative medicine.