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English definition of “nail sth down”

nail sth down

(UNDERSTAND) US informal phrasal verb with nail     /neɪl/ verb
to understand something completely , or to describe something correctly : We haven't been able to nail down the cause of the fire yet .Understanding and comprehendingDefining and explaining
(Definition of nail sth down (UNDERSTAND) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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