In BTS and Korean culture, “Oppa” (오빠) is a Korean term used by women to address an older male, such as a brother, friend, or significant other. It can also be used affectionately for a male celebrity, especially in K-pop culture.
Fans often call BTS members “Oppa” as a sign of endearment and admiration, even though the term is only appropriate for those who are younger than the BTS members. It’s a way for fans to express a close or affectionate connection to the group.