<prompt> false fixed firm beleif that the patient has subjectie ceainity is called ashallucinationdelusiondepresonalizationderealization  <response>: DELUSION - false fixed firm belief, subjective ceainity, compelling counterargument, impervious to other experiences and outside socio cultural and educational background it is a disorder of THOUGHT CONTENT Ref.Kaplon and sadock, synopsis of psychiatry, 11 th edition, pg. 195 