The observance of birth-days was common in early times (Job 1:4, 13, 18). They were specially celebrated in the land of Egypt (Genesis 40:20). There is no recorded instance in Scripture of the celebration of birth-days among the Jews. On the occasion of Herod's birth-day John the Baptist was beheaded (Matthew 14:6).

Noah Webster's New International Dictionary of the English Language

1. (n.) The day in which any person is born; day of origin or commencement.

2. (n.) The day of the month in which a person was born, in whatever succeeding year it may recur; the anniversary of one's birth.

3. (a.) of or pertaining to the day of birth, or its anniversary; as, birthday gifts or festivities.