Medical Dictionary

idée fixe

noun \(ˌ)ē-ˌdā-ˈfēks\
plural idées fixes \-ˈfēks(-əz)\

Medical Definition of IDÉE FIXE

:  a usually delusional idea that dominates the whole mental life during a prolonged period (as in certain mental disorders)—called also fixed idea

Browse

How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears