0 the day that is exactly a year or number of years after a person was born:
1 the day that is an exact year or number of years after a person was born:
Today is my mother’s 49th birthday.
My birthday is on the fourth of December.
Her birthday was getting nearer and I still hadn't bought her a present.
This is all very painful as we approach electroacoustic music's fiftieth birthday.
This lasted from shortly after his ®rst birthday until his second birthday.
Data were collected as soon as possible after the participant's birthday.
