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support (e.g. for an argument); backing; proof; evidence; corroboration; substantiation; guarantee; security
主張には裏付けが必要だ。
A claim needs evidence to back it up.
調査結果が彼の仮説の裏付けとなった。
The research results served as backing for his hypothesis.
裏付けのない噂を信じてはいけない。
You should not believe rumors without any backing.