proof
US /pruːf/
UK /pruːf/

1.
evidence or argument establishing a fact or the truth of a statement
:
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Do you have any proof that he was involved?
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The police found no proof of his guilt.
1.
demonstrate the truth or existence of (something) by evidence or argument
:
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Can you proof your claims with data?
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The new findings proof the previous theory.
2.
make (something) resistant to damage or penetration by something
:
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You should proof the fabric against water.
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The new coating will proof the metal from corrosion.
1.
resistant to damage or penetration by something
:
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This material is completely water-proof.
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The safe is fire-proof.