The Collaborative International Dictionary of English v.0.48:

katharsis \katharsis\ n.
   purging of emotional tensions; -- usually spelled
   catharsis.

   Syn: catharsis, abreaction.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Catharsis \Ca*thar"sis\, n. [NL., fr. Gr. ?. See Cathartic.]
   (Med.)
   1. A natural or artificial purgation of any passage, as of
      the mouth, bowels, etc.

   2. (Psychotherapy) The process of relieving an abnormal
      excitement by re["e]stablishing the association of the
      emotion with the memory or idea of the event that first
      caused it, and of eliminating it by complete expression
      (called the abreaction).
      [Webster 1913 Suppl.] Cathartic

WordNet (r) 3.0 (2006):

catharsis
    n 1: (psychoanalysis) purging of emotional tensions [syn:
         catharsis, katharsis, abreaction]
    2: purging the body by the use of a cathartic to stimulate
       evacuation of the bowels [syn: catharsis, katharsis,
       purgation]