Meaning

• A police spy or informer.

• An unpleasant person, especially one who makes things difficult for others.

Meaning

• To watch; to observe.

• To serve or behave as a spy or informer.

  "“If you nark on me, I’ll rip your arms off,” said Tim to his brother, as he passed him a joint."

• To annoy or irritate.

  "It really narks me when people smoke in restaurants."

• To complain.

  "He narks in my ear all day, moaning about his problems."

• (often imperative) To stop.

  "Nark it! I hear someone coming!"