de ri·gueur 
/dəˌriˈgɚ/ adjective
/dəˌriˈgɚ/ adjective formal : necessary if you want to be fashionable, popular, socially acceptable, etc.
▪ Dark sunglasses are de rigueur these days. ◊The phrase de rigueur comes from French.
▪ Dark sunglasses are de rigueur these days. ◊The phrase de rigueur comes from French.
