BSS or BooSeokSoon (부석순) is the official sub-unit of the South Korean group, SEVENTEEN, under Pledis Entertainment. It consists of three members: Seungkwan, DK, and Hoshi.

The name comes from the real names of the members: Boo (Boo Seung Kwan), Seok (Lee Seok Min – DK), Soon (Kwon Soon Young – Hoshi).

BSS debuted on March 21, 2018, with the single “거침없이 (Just Do It).”

Their second official release, a single album SECOND WIND, was released February 6, 2023.

On January 8, 2025, they released their second single album, TELEPARTY.