furtive in WordNet English dictionary

1. secret and sly or sordid
   "backstairs gossip"; "his low backstairs cunning"- A.L.Guerard; "backstairs intimacies"; "furtive behavior"
   backstair  backstairs  furtive 
   
2. 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"
   furtive  sneak  sneaky  stealthy  surreptitious