snitch

Noun

• someone acting as an informer or decoy for the police

Verb

• give away information about somebody
  • He told on his classmate who had cheated on the exam
    

• take by theft
  • Someone snitched my wallet!
    

Related words

• Synonyms: 
  fink , snitcher , stoolpigeon , stool pigeon , stoolie , sneak , sneaker , canary , hook , thieve , cop , knock off , glom