The story
- French · borrowed fromfolie à deux“madness for/of two [people]”
- English todayfolie à deux
Borrowed from French folie à deux (“madness for/of two [people]”).
Etymology from Wiktionary, CC BY-SA 4.0.
folie à deux
Today it means: A situation in which two people behave abnormally together in a way that neither of them would individually. Full definition →
French folie à deux