betray in WordNet English dictionary

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