stealthy
Definitions
Acting or moving in a cautious and surreptitious manner so as not to be seen or heard.
Designed or operating in a way that avoids detection by radar or other surveillance.
Examples
The stealthy cat crept across the floor without making a single sound.
The spy made a stealthy exit through the back door to avoid being seen.
Synonyms
sly furtive sneaky covert surreptitious clandestine underhanded