When to use official in Korean
Korean: 정식[ jeong-sik ]

When to use it
정식 means official or formal. It is used for something that is proper, approved, or done in the correct way. In clothing, it often means formal clothes for work, school events, weddings, or other important occasions.
Example sentences
오늘은 정식 옷을 입어요.
I wear formal clothes today.
학교 행사에는 정식 교복이 필요해요.
We need the official school uniform for the school event.
엄마가 결혼식에 정식 복장을 하라고 했어요.
Mom told me to wear formal clothes to the wedding.
그는 면접에 정식 셔츠를 입었어요.
He wore a formal shirt to the interview.
가게에서 정식 재킷을 샀어요.
I bought a formal jacket at the store.
여행 중이지만 저녁 파티에는 정식 옷차림을 했어요.
We were traveling, but we dressed formally for the dinner party.