Folie à deux (/fɒˈli ə ˈduː/; French pronunciation: ​[fɔli a dø]; French for “a madness shared by two”), or shared psychosis, is a psychiatric syndrome in which symptoms of a delusional belief are transmitted from one individual to another.[1] The same syndrome shared by more than two people may be called folie à trois, folie à quatre, folie en famille or even folie à plusieurs (“madness of many”). Recent psychiatric classifications refer to the syndrome as shared psychotic disorder.