- 1二十一歲生日（派對）；（一般用法）第二十一
Used as a noun, your twenty-first is your twenty-first birthday, or the party you have for it. This is very British and Australian. Historically, turning 21 was the age you became a legal adult in Britain, so the party was a big one — bigger than 18 — and even though the legal age moved to 18 long ago, the 'twenty-first' kept its special feeling. People say 'It's my twenty-first next week' or 'I'm going to Ben's twenty-first'. Written down you will see both 'twenty-first' and '21st'. Of course the word also just means 'number 21 in an order' — the twenty-first floor, the twenty-first century — but as a thing you can have and go to, it means the birthday.
twenty-first 作名詞時，指一個人的二十一歲生日，或為這個生日辦的派對，這是英式與澳式英語很常見的用法。歷史上 21 歲是英國的法定成年年紀，所以這場派對比 18 歲的更隆重；後來法定年齡改為 18 歲，但這個字仍保有特別的意味。例句像「It's my twenty-first next week」、「I'm going to Ben's twenty-first」，也可寫成 21st。若只是表示“第二十一個”，如「the twenty-first century」，那是一般用法。
組成twenty + first. English builds ordinal numbers by making only the last part ordinal: twenty + first, not 'twentieth-first'.
同家族的字
- thirty-firstsame pattern: the tens word stays plain, only the last part becomes an ordinal
- firstthe ordinal of 'one', which is the second half of this word
原始詞典資料4 筆記錄
以下是外部詞典記錄的用法，摘錄並精簡格式，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
twenty-firstadj
- 1
The ordinal form of the number twenty-one.
twenty-firstnoun
- 1
The person or thing in the twenty-first position.
- 2
One of twenty-one equal parts of a whole, usually written ¹⁄₂₁.
- 3
informalA party to celebrate a twenty-first birthday.
摘錄自 英文維基詞典 English Wiktionary，已精簡格式；依 CC BY-SA 4.0 授權使用，改動後的內容同樣以此授權提供。