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sure; no mistaking it; for certain; without doubt
この足跡は犯人のものに違い無い。
These footprints must belong to the culprit.
彼女が合格したのは努力の結果に違い無いだろう。
It must be the result of her efforts that she passed.
あの雲の様子だと明日は雨に違い無いと思う。
Looking at those clouds, I think it will definitely rain tomorrow.