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Synonyms for Betray (same or very similar meaning)

WordNet sense 1 (be sexually unfaithful to one's partner in marriage):
cheat, wander, cheat on

WordNet sense 2 (deliver to an enemy by treachery):

WordNet sense 3 (disappoint, prove undependable to; abandon, forsake):

WordNet sense 4 (reveal unintentionally):

WordNet sense 5 (cause someone to believe an untruth):
deceive, lead astray

WordNet sense 6 (give away information about somebody):
denounce, grass, rat, shit, shop, snitch, stag, give away, tell on

From the ODE community, based on WordNetadd/edit