twenty-firsts是twenty-first的复数

twenty-first

美

英

n.21 岁生日；21 岁生日庆典
网络第二十一；第二十一的；第二十一日

复数：twenty-firsts

英英

网络释义

n.	1. someone’s 21st birthday, when they often have a party to celebrate the fact that they have become a full adult