de ri·gueur /də riːˈɡɜː $ -ˈɡɜːr/ adjectiveadj [not before noun] FASHIONABLEconsidered to be necessary if you want to be accepted, fashionable etc – used humorously 〔按照礼节、时尚等〕必需的〔幽默用法〕 the gleaming white teeth that are de rigueur for movie stars 影星必不可少的亮白牙齿
de rigueur• Tuxedos are de rigueur at the event.