Meaning of “betray” - Learner’s Dictionary

betray

verb [ T ] uk us /bɪˈtreɪ/
PERSON

B2 to behave in a dishonest or cruel way to someone who trusts you:

When I heard what he had said about me, I felt betrayed.
SECRETS

If you betray your country or an organization, you give secret information to its enemies or to other organizations.

EMOTION

to show an emotion that you were trying to hide:

Her face was calm, but her hands betrayed her nervousness.

(Definition of “betray” from the Cambridge Learner’s Dictionary © Cambridge University Press)