to hurt someone who trusts you by being disloyal to them, especially by helping their enemies or sharing harmful information
Judas betrayed Jesus for thirty silver coins.
The spy betrayed his country by selling secrets to a foreign agent.
✦ Middle English betraien, from be- + Old French traïr “to betray,” from Latin tradere “to hand over.”
to reveal something hidden, such as a feeling or secret, often without intending to
Her trembling voice betrayed her fear during the interview.
A sudden blush betrayed her embarrassment.
to deceive or mislead someone so they make a mistake
Appearances can betray even the wisest traveler.
The calm sea betrayed the storm that lurked beneath.
an act of breaking trust or loyalty, especially by helping an enemy or revealing secrets
Robin felt deep betrayal when his best friend shared his secret with everyone.
The spy’s betrayal changed the course of the war.
✦ Formed from the verb "betray" + suffix "-al" in Middle English, meaning the act or result of betraying.
something, such as a movement, expression, or sound, that unintentionally reveals a hidden thought or feeling
A faint smile was a betrayal of her true feelings.
The tremor in his hand was a subtle betrayal of nervousness.
✦ Extension of the main sense 'act of betraying' to describe any revealing sign, first recorded in English in the 17th century.
