idee fixe

Noun

idée fixe (plural idées fixes)

1. An idea dominating the mind and maintained despite evidence to the contrary; (loosely), an obsession.
   • “There is the condition which the modern French psychologists have called the ‘idée fixe,’ which may be trifling in character, and accompanied by complete sanity in every other way. A man who had read deeply about Napoleon, or who had possibly received some hereditary family injury through the...1904 April 30, A[rthur] Conan Doyle, “The Adventure of the Six Napoleons”, in The Return of Sherlock Holmes, New York, N.Y.: McClure, Phillips & Co., published February 1905, →OCLC, page 212

   Synonyms:

   fixed idea

2. A recurring musical theme; a leitmotif.
   • a definite musical figure, called the 'idée fixe,' unifying the work throughout by its constant reappearance in various aspects and surroundings1922, Grove's Dictionary of Music and Musicians, volume 4, page 793