dissociative identity disorder UK /dɪˈsəʊʃi.ətɪv aɪˈdɛntɪti dɪsˈɔːdə/US /dɪˈsoʊʃi.ətɪv aɪˈdɛntɪti dɪsˈɔɹdɚ/ noun1 •A mental disorder characterized by the presence of two or more personality states or distinct identities that repeatedly take control of a person's behavior. formsdissociative identity disorders