folie à deux

/F OW1 L IY0 D UH0/
noun
  1. 1

    A rare syndrome in which a symptom of psychosis (particularly a paranoid or delusional belief) is transmitted from one person to another.

Translate “folie à deux” into another language

Source: https://en.wiktionary.org/wiki/folie%20%C3%A0%20deux