twenty-first
🇺🇸
/ˌtwenti ˈfɜːrst/
🇬🇧
/ˌtwenti ˈfɜːst/
The celebration or event that marks someone's 21st birthday.
On her twenty-first, she received a trip to Paris as a gift.
彼女の二十一歳の誕生日に、パリへの旅行がプレゼントとして受け取られました。