fifteenth       
 ordinal number uk/ˌfɪfˈtiːnθ/ us/ˌfɪfˈtiːnθ/
 第十五(的)
15th written as a word
  Today is the fifteenth (of June). 今天是(6月)15日。 
 fifteenth      
noun [ C ] uk/ˌfɪfˈtiːnθ/ us/ˌfɪfˈtiːnθ/
 十五分之一
one of 15 equal parts of something