十五日的英文怎么说

"fifteenth" 是 "十五日" 的英语表达方式。

其来源是通过将 "fifteen"（十五）和 "th"（第几）结合在一起而得到。

例句：

"I will see you on the fifteenth." (我将在十五日见到你。)
"The fifteenth of next month is a hopday." (下个月的十五日是假日。)
"We are going to have a party on the fifteenth." (我们将在十五日举行派对。)