surreptitious surreptitious /ˌsɝːəpˈtɪʃəs/

adjective

1. Conducted with or marked by hidden aims or methods  ( cloak-and-dagger , hole-and-corner , hugger-mugger , clandestine , hush-hush , secret , surreptitious , undercover , underground )
   conducted with or marked by hidden aims or methods
    Clandestine intelligence operations
   clandestine intelligence operations
    Cloak-and-dagger activities behind enemy lines
   cloak-and-dagger activities behind enemy lines
    Hole-and-corner intrigue
   hole-and-corner intrigue
    Secret missions
   secret missions
    A secret agent
   a secret agent
    Secret sales of arms
   secret sales of arms
    Surreptitious mobilization of troops
   surreptitious mobilization of troops
    An undercover investigation
   an undercover investigation
    Underground resistance
   underground resistance
   
2. Marked by quiet and caution and secrecy; taking pains to avoid being observed  ( sneak , sneaky , surreptitious , furtive , stealthy )
   marked by quiet and caution and secrecy; taking pains to avoid being observed
    A furtive manner
   a furtive manner
    A sneak attack
   a sneak attack
    Stealthy footsteps
   stealthy footsteps
    A surreptitious glance at his watch
   a surreptitious glance at his watch