Betray

1. verb

   disappoint, prove undependable to; abandon, forsake

   “His sense of smell failed him this time”

   Similar: fail

2. verb

   be sexually unfaithful to one's partner in marriage

   “She cheats on her husband”

   Similar: cheat on, cheat, cuckold, wander

3. verb

   give away information about somebody

   “He told on his classmate who had cheated on the exam”

   Similar: denounce, tell on, give away, rat, grass, shit

4. verb

   cause someone to believe an untruth

   “The insurance company deceived me when they told me they were covering my house”

   Similar: deceive, lead astray