idée fixe       
noun [ C ] uk/ˌiː.deɪ ˈfiːks/ us/ˌiː.deɪ ˈfiːks/  idées fixes /ˌiː.deɪ ˈfiːks/ /ˌiː.deɪ ˈfiːks/
 固定观念;偏执
a belief that someone refuses to change their mind about, even though it may be wrong
  This point of view has become something of an idée fixe among political commentators. 这一观点成了政治评论员们的固定观念。