twen·ty-first
noun/ˌtwenti ˈfɜːst/
/ˌtwenti ˈfɜːrst/
[singular] (especially British English, informal)- a person’s 21st birthday and the celebrations for this occasion
21 岁生日；21 岁生日庆典 - She’s having a party on her twenty-first.
她二十一岁那年要举办一场聚会。 - His parents gave him a car for his twenty-first.
他的父母在他二十一岁的时候给了他一辆车。
- She’s having a party on her twenty-first.