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English definition of “back sth up”

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back sth up

verb uk phrasal verb with back   /bæk/ us  
C2 to prove something is true: His claims are backed up by recent research.B2 to make an extra copy of computer information: Make sure you back up your files.
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(Definition of back sth up phrasal verb, verb from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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