cause someone to believe an untruth; "The insurance company deceived me when they told me they were covering my house";
reveal unintentionally; "Her smile betrayed her true feelings";
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";
deliver to an enemy by treachery; "Judas sold Jesus"; "The spy betrayed his country";
be sexually unfaithful to one''s partner in marriage; "She cheats on her husband"; "Might her husband be wandering?";