생신 (saengsin) means “birthday” | MotiTan Korean Dictionary

More examples

오늘은 생신이라서 집에서 작은 파티를 했어요.o neu reun saeng si ni ra seo chi be seo cha geun pa ti reul hae sseo yo

Today is your birthday, so we had a small party at home.

A birthday viewed with special respect because it belongs to an older or honored person.

생일saengil: The date of a person's birth and the day celebrated every year.
돌tol: A baby's special celebration after living for one year.

어른이나 존경하는 사람의 생일을 공손하게 이르는 말.eo reu ni na chon gyeong ha neun sa ra mui saeng i reul kong son ha ge i reu neun mal

This word comes from Sino-Korean elements connected with birth and a calendrical day, and it developed into a respectful term for birthday.

Korean changes the birthday word according to respect, so this form is used for an older or honored person rather than casually for everyone.