What is the meaning of sneak?

noun

• A person who is regarded as underhanded and furtive and contemptible.
• Someone who prowls or sneaks about; usually with unlawful intentions.
  • synonyms: prowler, stalker
• Someone acting as an informer or decoy for the police.
  • synonyms: fink, snitch, snitcher, stoolpigeon, stool pigeon, stoolie, sneaker, canary

verb

• To go stealthily or furtively.
  • usage: ".. Stead of sneaking around spying on the neighbor's house"
  • synonyms: mouse, creep, pussyfoot
• Put, bring, or take in a secretive or furtive manner.
  • usage: "sneak a look"; "sneak a cigarette"
• Make off with belongings of others.
  • synonyms: pilfer, cabbage, purloin, pinch, abstract, snarf, swipe, hook, filch, nobble, lift
• Pass on stealthily.
  • usage: "He slipped me the key when nobody was looking"
  • synonyms: slip

adjective

• Marked by quiet and caution and secrecy; taking pains to avoid being observed.
  • usage: "a furtive manner"; "a sneak attack"; "stealthy footsteps"; "a surreptitious glance at his watch"
  • synonyms: furtive, sneaky, stealthy, surreptitious