birthday 2023.03.13 birthdayとは 意味・定義・例文 Noun 名詞 バ〜スデイ US /ˈbɜrθˌdeɪ/ UK /ˈbɜːθdeɪ/ 1. the anniversary of the day on which you were born 誕生日 "When is your birthday?" "It's March 26."