A neurological and physiological symptom that is characterized by a marked psychomotor disturbance that may involve stupor or mutism, negativism, rigidity, purposeless excitement, echolalia, echopraxia, and inappropriate or bizarre posturing and is associated with various medical conditions (as schizophrenia and mood disorders). [ url:http://www2.merriam-webster.com/cgi-bin/mwmednlm?book=Medical&va=catatonia ]