sneak

Adjective

• 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
    

Noun

• someone acting as an informer or decoy for the police

• someone who prowls or sneaks about; usually with unlawful intentions

• a person who is regarded as underhanded and furtive and contemptible

Verb

• pass on stealthily
  • He slipped me the key when nobody was looking
    

• make off with belongings of others

• put, bring, or take in a secretive or furtive manner
  • sneak a look
    
  • sneak a cigarette
    

• to go stealthily or furtively
  • ..stead of sneaking around spying on the neighbor's house
    

Related words

• Synonyms: 
  furtive , sneak(a) , sneaky , stealthy , surreptitious , fink , snitch , snitcher , stoolpigeon , stool pigeon , stoolie , sneaker , canary , prowler , stalker , slip , mouse , creep , pussyfoot