1.reveal unintentionally;
Her smile betrayed her true feelings
2.deliver to an enemy by treachery;
Judas sold Jesus
3.disappoint, prove undependable to; abandon, forsake;
His sense of smell failed him this time
4.be sexually unfaithful to one's partner in marriage;
She cheats on her husband
5.give away information about somebody;
He told on his classmate who had cheated on the exam
6.cause someone to believe an untruth;
The insurance company deceived me when they told me they were covering my house