/ˌsʌrəpˈtɪʃəs/ – adjective
Definition: lén lút, kín đáo, bí mật.
A more thorough explanation: “Surreptitious” is an adjective that refers to something done, made, or acquired by stealth or in a secretive manner, especially in order to avoid being noticed or detected.
Example: The investigator obtained surreptitious recordings of the suspect’s conversations without their knowledge or consent.