Definition of Betray

Verb: betray bi'trey

Reveal unintentionally
"Her smile betrayed her true feelings";
- bewray [archaic]
Deliver to an enemy by treachery
"The spy betrayed his country";
- sell
Disappoint, prove undependable to; abandon, forsake
"His sense of smell betrayed him this time";
- fail
Be sexually unfaithful to one's partner in marriage
"She betrays her husband";
- cheat on, cheat, cuckold, wander
Give away information about somebody
"He betrayed his classmate who had cheated on the exam";
- denounce, tell on, give away, rat, grass, shop, snitch, stag, squeak
Cause someone to believe an untruth
"The insurance company betrayed me when they told me they were covering my house";
- deceive, lead astray