sneak
noun(sneak)
someone who prowls or sneaks about; usually with unlawful intentions
sneak
verb(sneak)
make off with belongings of others
Synonyms: abstract, 
cabbage, 
filch, 
hook, 
lift, 
nobble, 
pilfer, 
pinch, 
purloin, 
snarf, 
swipe, 
 sneak
noun(sneak)
someone acting as an informer or decoy for the police
sneak
adjective(sneak)
marked by quiet and caution and secrecy; taking pains to avoid being observed
Examples:
A sneak attack. 
sneak
verb(sneak)
pass on stealthily
sneak
verb(sneak)
to go stealthily or furtively
Examples:
..stead of sneaking around spying on the neighbor's house. 
sneak
noun(sneak)
a person who is regarded as underhanded and furtive and contemptible
sneak
verb(sneak)
put, bring, or take in a secretive or furtive manner
Examples:
Sneak a look. 
Sneak a cigarette.