beyond a shadow of a doubt

• beyond a shadow of doubt, beyond the shadow of a doubt, without a shadow of a doubt

From shadow of a doubt.

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beyond a shadow of a doubt

1. (idiomatic) Without any doubt or hesitation at all.

   I knew beyond a shadow of a doubt that my sister would want to go to the concert.

   • 1945 April 16, Harry S. Truman, 10:06 from the start, in MP72-20 President Roosevelt’s Funeral and Procession; Truman – New President of U.S.‎^[1], Harry S. Truman Presidential Library and Museum, National Archives Identifier: 595162:

     So that there can be no possible misunderstanding, both Germany and Japan can be certain beyond any shadow of a doubt that America will continue to fight for freedom until no vestige of resistance remains. Our demand has been and it remains unconditional surrender.

• beyond reasonable doubt

• “without beyond a shadow of a doubt” in Longman Dictionary of Contemporary English, Longman.
• “beyond without a shadow of a doubt” (US) / “beyond without a shadow of a doubt” (UK) in Macmillan English Dictionary.
• “beyond a shadow of a doubt”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.