What is the meaning of ratting?

noun

• To furnish incriminating evidence to an officer of the law (usually in return for favors.
  • synonyms: informing

verb

• Desert one's party or group of friends, for example, for one's personal advantage.
  • synonyms: rat
• Employ scabs or strike breakers in.
  • synonyms: rat
• Take the place of work of someone on strike.
  • synonyms: fink, scab, rat, blackleg
• Give (hair) the appearance of being fuller by using a rat.
  • synonyms: rat
• Catch rats, especially with dogs.
  • synonyms: rat
• Give away information about somebody.
  • usage: "He told on his classmate who had cheated on the exam"
  • synonyms: denounce, tell on, betray, give away, rat, grass, shit, shop, snitch, stag