[verb] pass on stealthily; "He slipped me the key when nobody was looking" Synonyms: slip
[adjective] marked by quiet and caution and secrecy; taking pains to avoid being observed; "a furtive manner"; "a lurking prowler"; "a sneak attack"; "stealthy footsteps"; "a surreptitious glance at his watch"; "someone skulking in the shadows" Synonyms: furtive, lurking, skulking, stealthy, surreptitious