adj. conducted with or marked by hidden aims or methods; "clandestine intelligence operations"; "cloak-and-dagger activities behind enemy lines"; "hole-and-corner intrigue"; "secret missions"; "a secret agent"; "secret sales of arms"; "surreptitious mobilization of troops"; "an undercover investigation"; "underground resistance"

adj. marked by deception; "achieved success in business only by underhand methods"

adj. marked by quiet and caution and secrecy; taking pains to avoid being observed; "a furtive manner"; "a sneak attack"; "stealthy footsteps"; "a surreptitious glance at his watch"

adj. acting together in secret toward a fraudulent or illegal end

adj. not accessible to view; "concealed (or hidden) damage"; "in stormy weather the stars are out of sight"

adj. having its true character concealed with the intent of misleading; "hidden agenda"; "masked threat"

adj. with your identity concealed

adj. protected from danger or bad weather; "a sheltered harbor"

adj. designed and carried out secretly or confidentially; "a sub-rosa report"; "has their under-the-table backing"

adj. lying beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed); "subterranean motives for murder"; "looked too closely for an ulterior purpose in all knowledge"- Bertrand Russell

adj. not made known

adj. open and observable; not secret or hidden; "an overt lie"; "overt hostility"; "overt intelligence gathering"; "open ballots"