identity disorder

n. 1. A disorder characterized by the presence of two or more distinct personalities or identities in the same person who recurrently exchange control of the person and who may have only some knowledge of each other and the history of the person involved. 2. A disorder characterized by a strong and persistent sense that one is or should be the other gender and discomfort with one’s socially assigned gender, which generates significant distress and impairment in the person's life.