From Longman Dictionary of Contemporary Englishwithout/beyond a shadow of a doubtwithout/beyond a shadow of a doubtCERTAINLY/DEFINITELYused to say that something is definitely true Without a shadow of a doubt, he’s the most talented player we have. → shadow
Examples from the Corpus
without/beyond a shadow of a doubt• Don't ask me how - but I knew it without a shadow of a doubt.• Now she knew without a shadow of doubt that she wasn't. 