偷偷 (tōu tōu) means “stealthily; secretly; covertly; furtively; on the sly”. It is an HSK 5 Chinese word in the HSK 3.0 vocabulary.
Practice each character:
他偷偷地离开了教室。
Tā tōutōu de líkāi le jiàoshì.
He secretly left the classroom.
Updated: 2026-07-18