생신이 · 생신을
birthday (honorific)
Example
다음 주 토요일이 아버지 생신이에요.
Next Saturday is my father's birthday.
Word parts
생 birth+신 day, time
Literally 'birth day': 生 'birth' + 辰 'day, time'.
Good to know
The plain word is 생일; use 생신 for parents, grandparents and other elders, and congratulate them with 생신 축하드려요.
Related words