Idée fixe (psychology)

Idée fixe is a French phrase that means "fixed idea". In psychology, it is when a person has a strong thought or belief that won't go away and makes it hard for them to think about anything else. It can interfere with the person's life by making it hard for them to concentrate on other things, or by making them very upset. This is different from regular stubbornness because it can be a symptom of mental problems like OCD or schizophrenia.