Webster’s Revised Unabridged Dictionary · 1913
Birthday
Birth′day′ (bẽrth′dā′), n. 1. The day in which any person is born; day of origin or commencement.
Those barbarous ages past, succeeded next The birthday of invention. Cowper.
2. The day of the month in which a person was born, in whatever succeeding year it may recur; the anniversary of one's birth.
This is my birthday; as this very day Was Cassius born. Shak.
Birth′day′, a. Of or pertaining to the day of birth, or its anniversary; as, birthday gifts or festivities.