Synonyms:
clandestine, cloak-and-dagger, hole-and-corner(a), hugger-mugger, hush-hush, secret, surreptitious, undercover, underground
Meaning: 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"
Synonyms:
furtive, sneak(a), sneaky, stealthy, surreptitious
Meaning: 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"
Usage examples
The State leaders may even make a merit of their surreptitious invasions of it on the ground of some temporary convenience, exemption, or advantage.