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English definition of “birthday”

birthday

noun [C] uk   /ˈbɜːθ.deɪ/ us    /ˈbɝːθ-/
A1 the day that is exactly a year or number of years after a person was born: Happy birthday, Flavio! Are you going to Ellen's birthday party next week? It's her 21st birthday.Describing age and birthdaysBirthdays and anniversaries
(Definition of birthday from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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