multiple personality disorder
noun /ˌmʌltɪpl ˌpɜːsəˈnæləti dɪsɔːdə(r)/
/ˌmʌltɪpl ˌpɜːrsəˈnæləti dɪsɔːrdər/
(also less frequent split personality disorder)
(psychology)- a rare condition in which a person seems to have one or more different personalities