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English definition of “betray”

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betray

verb [T] uk   /bɪˈtreɪ/ us  

betray verb [T] (NOT LOYAL)

B2 to not be loyal to your country or a person, often by doing something harmful such as helping their enemies: He was accused of betraying his country during the war. She felt betrayed by her mother's lack of support. For years they betrayed the UK's secrets to Russia. formal He promised never to betray his wife (= never to leave her for another person). formal If someone betrays something such as a promise, they do not do what they promised: The president has been accused of betraying his election promises. By staying out so late, they have betrayed my trust (= disappointed me because I had trusted them not to).
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betray verb [T] (SHOW)

to show feelings, thoughts, or a particular characteristic without intending to: If he is nervous on stage, he does not betray it. Although she often seems quite cold, her smiling eyes betray her true nature.
(Definition of betray from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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