What is the meaning of the word "betray"?

Definitions:

to be sexually unfaithful to one's partner in marriage verb
- They betrayed their partner publicly.
to cause someone to believe an untruth verb
- The ideologue betrayed their followers.
to deliver to an enemy by treachery verb
- They betrayed us by leaking secrets to the other team.
to disappoint, prove undependable to verb
- You betrayed me again.
to give away information about somebody verb
- I betrayed my friend's job search to their current employer.
to reveal unintentionally verb
- Your smile betrayed your true feelings.