verb

• (transitive) To deliver into the hands of an enemy by treachery or fraud, in violation of trust; to give up treacherously or faithlessly.
  "An officer betrayed the city."
• (transitive) To prove faithless or treacherous to, as to a trust or one who trusts; to be false to; to deceive.
  "to betray a person or a cause"
• (transitive) To violate the confidence of, by disclosing a secret, or that which one is bound in honor not to make known.
• (transitive) To disclose (a secret, etc.) in deliberate violation of someone’s confidence.
  "The dead leap at the throat, destroy The meaning of the day; dark forms Have scaled your walls, and spies betray Old secrets to amorphous swarms."