Proof is the evidence that shows something is true or valid. When you show the logical steps that take you from your hypothesis that the world is round to the conclusion that it is, you’re formulating a proof.

Photographic prints that haven’t been touched up are also called proofs, and that’s also what you call the first copy of a printed text, before it’s checked for errors and corrected. When you check a text for errors, you’re proofing. If your poker strategy is foolproof, even somebody who knows nothing about poker — a poker fool, that is — can’t get it wrong. Proof is a word you’ll see on bottles of alcohol, too: 90-proof rum means it’s 45% alcohol.

Definitions of proof
  1. noun

    any factual evidence that helps to establish the truth of something

    “if you have any
    proof for what you say, now is the time to produce it”
    cogent evidence
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    check, confirmation, substantiation, verification

    additional proof that something that was believed (some fact or hypothesis or theory) is correct
    establishment, validation

    the cognitive process of establishing a valid proof
    bed check

    a check that everyone is in bed by the time they should be

    an instance of confirming something by considering information from several sources
    odd-even check, parity check, redundancy check

    a system of checking for errors in computer functioning

    a digit representing the sum of the digits in an instance of digital data; used to check whether errors have occurred in transmission or storage
    type of:

    evidence, grounds

    your basis for belief or disbelief; knowledge on which to base belief

  2. noun

    a formal series of statements showing that if one thing is true something else necessarily follows from it

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    mathematical proof

    proof of a mathematical theorem
    logical proof

    proof of a logical theorem
    demonstration, monstrance

    proof by a process of argument or a series of proposition proving an asserted conclusion
    type of:

    argument, statement

    a fact or assertion offered as evidence that something is true

  3. noun

    the act of validating; finding or testing the truth of something

    substantiation, validation
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    authentication, certification

    validating the authenticity of something or someone
    documentation, support

    documentary validation
    monetisation, monetization

    establishing something (e.g. gold or silver) as the legal tender of a country

    the act of proving that an instrument purporting to be a will was signed and executed in accord with legal requirements
    type of:

    determination, finding

    the act of determining the properties of something, usually by research or calculation

  4. noun

    (printing) an impression made to check for errors

    test copy, trial impression
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    galley proof

    a proof taken before the type is broken up to print pages
    foundry proof

    a proof taken from a form before duplicate plates are made
    type of:

    impression, printing

    all the copies of a work printed at one time

  5. noun

    a trial photographic print from a negative

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    type of:

    photographic print, print

    a printed picture produced from a photographic negative

  6. verb

    read for errors

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    type of:

    ascertain, assure, check, control, ensure, insure, see, see to it

    be careful or certain to do something; make certain of something

  7. verb

    make or take a proof of, such as a photographic negative, an etching, or typeset

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    type of:

    create, make, produce

    create or manufacture a man-made product

  8. verb

    make resistant (to harm)

    proof the materials against shrinking in the dryer”
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    make safe against bombings

    make bulletproof
    child-proof, childproof

    make safe against children
    foolproof, goof-proof, goofproof

    proof against human misuse or error

    make resistant to fire

    make resistant to bad weather
    type of:


    gain strength

  9. adjective

    (used in combination or as a suffix) able to withstand


    imperviable, impervious

    not admitting of passage or capable of being affected
  10. noun

    a measure of alcoholic strength expressed as an integer twice the percentage of alcohol present (by volume)

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    type of:

    amount, measure, quantity

    how much there is or how many there are of something that you can quantify

  11. verb

    knead to reach proper lightness

    proof dough”
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    type of:

    knead, work

    make uniform

  12. verb

    activate by mixing with water and sometimes sugar or milk

    proof yeast”
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    type of:

    alter, change, modify

    cause to change; make different; cause a transformation

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