誕生日|たんじょうびtanjoubi

1. nounbirthday
   今日きょうは、妹いもうとの誕生日たんじょうびです。↗

   Today is my sister's birthday.

• SynonymバースデーCasualバースデー is a colloquial loanword from English, typically used in casual conversation, commercial contexts, and compounds such as バースデーケーキ or バースデーパーティー rather than as a plain substitute for 誕生日.

誕生日 is the standard word for birthday in all contexts; バースデー is a colloquial loanword used mainly in casual speech, advertising, and set phrases like バースデーケーキ.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 生うまれた日ひ。
2. 語義ごぎ1と月日つきひが同おなじ日ひ。