Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun birthday

2 senses of birthday

Sense 1
birthday -- (an anniversary of the day on which a person was born (or the celebration of it))
       => anniversary, day of remembrance -- (the date on which an event occurred in some previous year (or the celebration of it))

Sense 2
birthday, natal day -- (the date on which a person was born)
       => date, day of the month -- (the specified day of the month; "what is the date today?")