What is the meaning of betray?

verb

• Reveal unintentionally.
  • usage: "Her smile betrayed her true feelings"
  • synonyms: bewray
• Deliver to an enemy by treachery.
  • usage: "Judas sold Jesus"; "The spy betrayed his country"
  • synonyms: sell
• Disappoint, prove undependable to; abandon, forsake.
  • usage: "His sense of smell failed him this time"; "His strength finally failed him"; "His children failed him in the crisis"
  • synonyms: fail
• Be sexually unfaithful to one's partner in marriage.
  • usage: "She cheats on her husband"; "Might her husband be wandering"
  • synonyms: cheat on, cheat, cuckold, wander
• Give away information about somebody.
  • usage: "He told on his classmate who had cheated on the exam"
  • synonyms: denounce, tell on, give away, rat, grass, shit, shop, snitch, stag
• Cause someone to believe an untruth.
  • usage: "The insurance company deceived me when they told me they were covering my house"
  • synonyms: deceive, lead astray