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English definition of “rat on sb/sth”

rat on sb/sth

verb uk phrasal verb with rat   /ræt/ slang disapproving us  
to not be loyal to someone, especially by giving away secret information about them, or to fail to do something that you said you would do: He ratted on us. They ratted on the deal.
(Definition of rat on sb/sth from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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Translations of “rat on sb/sth”

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