folie à deux

noun

fo·​lie à deux fȯ-lē-ä-ˈdœ  ˌfä-lē-ˌä-ˈdər 

-ˈdə

: the presence of the same or similar delusional ideas in two persons closely associated with one another

Word History

Etymology

French, literally, double madness

First Known Use

circa 1892, in the meaning defined above

Medical Definition

folie à deux

noun

-(ˌ)ä-ˈdœ̅, -ˈdə

plural folies à deux

ˌfō-ˈlē(z)-(ˌ)ä-

: the presence of the same or similar delusional ideas in two persons closely associated with one another