surreptitious

surreptitious
    adj 1: 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" [syn: {furtive}, {sneak(a)}, {sneaky},
           {stealthy}, {surreptitious}]
    2: 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" [syn: {clandestine},
       {cloak-and-dagger}, {hole-and-corner(a)}, {hugger-mugger},
       {hush-hush}, {secret}, {surreptitious}, {undercover},
       {underground}]
    

Surreptitious \Sur`rep*ti"tious\, a. [L. surreptitius, or
   subreptitius, fr. surripere, subripere, to snatch away, to
   withdraw privily; sub- under + rapere to snatch. See {Sub-},
   and {Ravish}.]
   Done or made by stealth, or without proper authority; made or
   introduced fraudulently; clandestine; stealthy; as, a
   surreptitious passage in an old manuscript; a surreptitious
   removal of goods. -- {Sur`rep*ti"tious*ly}, adv.
   [1913 Webster]
    

SURREPTITIOUS. That which is done in a fraudulent stealthy manner. 
    

70 Moby Thesaurus words for "surreptitious":
      artful, back-door, backstairs, calculating, chiseling, clandestine,
      collusive, concealed, covert, covinous, crafty, cunning, deceitful,
      doggo, false, falsehearted, feline, finagling, fraudulent, furtive,
      guileful, hidden, hidden out, hidlings, hole-and-corner,
      hugger-mugger, hush-hush, in ambush, in hiding, in the wings,
      indirect, insidious, lurking, on the sly, on tiptoe, private,
      privy, prowling, pussyfoot, pussyfooted, quiet, scheming, secret,
      secretive, sharp, shifty, skulking, slinking, slinky, slippery,
      sly, sneaking, sneaky, stealing, stealthy, treacherous, trickish,
      tricky, two-faced, under cover, under-the-counter, under-the-table,
      undercover, underground, underhand, underhanded, unobtrusive,
      veiled, waiting concealed, wily