When to use older sister in Korean
Korean: 언니[ eon-ni ]

When to use it
An older sister is your sister who is older than you. In Korean, a girl or woman says (언니) when talking to or calling her older sister. It is a warm, common family word you hear a lot in everyday life.
Example sentences
언니랑 저녁을 먹어요.
I eat dinner with my older sister.
언니가 학교에 데려다줘요.
My older sister takes me to school.
공원에서 언니와 사진을 찍었어요.
I took a photo with my older sister at the park.
언니, 이거 뭐예요?
Older sister, what is this?
언니랑 마트에서 과자를 샀어요.
I bought snacks with my older sister at the mart.
작년에 언니와 부산에 갔어요.
I went to Busan with my older sister last year.