Webster's Revised Unabridged Dictionary · 1913

Birthday

Birthday (bẽrth"dā`) , noun

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. — Shakespeare

Birthday , adjective

Of or pertaining to the day of birth, or its anniversary; as, birthday gifts or festivities.