birth⋅day/ˈbɜrθˌdeɪ/
Show Spelled Pronunciation [burth-dey] Show IPA Use birthday in a Sentence –noun
1. the anniversary of a birth.
2. the day of a person's birth.
3. a day marking or commemorating the origin, founding, or beginning of something.
4. the festivities or celebration marking such a day or anniversary.