folie à deux.

A delusional belief shared by two closely associated people, traditionally understood as transmitted or reinforced within the pair.

Use it for

Words that belong together

• a case of folie à deux
• folie à deux between partners
• a shared folie à deux

On the page

The report called it folie à deux, a term that explained their agreement without explaining the scratches on the door.

What began as her private conviction became a folie à deux in which each supplied the other's missing evidence.

Usage notes

Primary category: horror. Forms: Usually uncountable; the term names a shared condition or phenomenon, not two separate people. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings.