furtive

Adjective

• secret and sly or sordid
  • backstairs gossip
    
  • his low backstairs cunning- A.L.Guerard
    
  • backstairs intimacies
    
  • furtive behavior
    

• 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
    

Related words

• Synonyms: 
  backstair , backstairs , sneak(a) , sneaky , stealthy , surreptitious