fo·lie à deux \(ˌ)fōˌlē(ˌ)äˈdə(r.), -də̄\noun (pluralfolies à deux \-ē(ˌ)(z)ä-\) Etymology: French, literally, double madness : the presence of the same or similar delusional ideas in two persons closely associated with one another; especially: the result of transmission of delusional ideas from one person to another