[n] an anniversary of the day on which a person was born
[n] the date on which a person was born
natal day - (3 syllables)
\Birth"day`\ (b[~e]rth"d[=a]`), 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.