transient       
 adjective  formal uk/ˈtræn.zi.ənt/ us/ˈtræn.zi.ʃənt/
 短暂的,转瞬即逝的;暂时的
lasting for only a short time; temporary
  A glass of whisky has only a transient warming effect. 一杯威士忌只能使人暖和一会儿。 
 The city has a large transient population (= many people who are living in it only temporarily). 这个城市有大量的暂住人口。 
 transient       
noun [ C ] mainly US formal uk/ˈtræn.zi.ənt/ us/ˈtræn.zi.ʃənt/
 暂住者;流动人口
someone who lives only temporarily in a place
  It's an organization set up to provide money and help for transients. 这个组织建立的目的就是给暂住者提供钱款和帮助。