surreptitiously
🇺🇸
/ˌsɜːrəpˈtɪʃəsli/
🇬🇧
/ˌsʌrəpˈtɪʃəsli/
in a way that is meant to be hidden or not easily seen
The spy took the document and left the room surreptitiously.
間諜偷偷地拿了文件,然後離開了房間。