the Third World       
noun uk/ˌθɜːd ˈwɜːld/ us/ˌθɝːd ˈwɝːld/
 第三世界
the countries of Africa, South America, and Asia that have less developed industries
  She does a lot of work in the Third World. 她在第三世界国家做了大量工作。 
 a Third World country/economy 第三世界国家/经济