(1)   The act of validating; finding or testing the truth of something
(2)   A trial photographic print from a negative
(3)   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"
(4)   (printing) an impression made to check for errors
(5)   A formal series of statements showing that if one thing is true something else necessarily follows from it
(6)   A measure of alcoholic strength expressed as an integer twice the percentage of alcohol present (by volume)


(7)   Make resistant (to harm)
"Proof the materials against shrinking in the dryer"
(8)   Activate by mixing with water and sometimes sugar or milk
"Proof yeast"
(9)   Read for errors
"I should proofread my manuscripts"
(10)   Knead to reach proper lightness
"Proof dough"
(11)   Make or take a proof of, such as a photographic negative, an etching, or typeset


< < < < ; see prove.


  1. Any effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.
    • Edmund Spenser,
      For whatsoever mother wit or art Could work, he put in proof.
    • Ford,
      You shall have many proofs to show your skill.
    • Ure,
      Formerly, a very rude mode of ascertaining the strength of spirits was practiced, called the proof.
  2. The degree of evidence which convinces the mind of any truth or fact, and produces belief; a test by facts or arguments which induce, or tend to induce, certainty of the judgment; conclusive evidence; demonstration.
    • William Shakespeare,
      I'll have some proof.
    • Ralph Waldo Emerson,
      It is no proof of a man's understanding to be able to confirm whatever he pleases.
    • 1990 October 28, Paul Simon, “Proof”, The Rhythm of the Saints, Warner Bros.
      Faith, faith is an island in the setting sun / But proof, proof is the bottom line for everyone
  3. The quality or state of having been proved or tried; firmness or hardness which resists impression, or doesn't yield to force; impenetrability of physical bodies.
  4. Firmness of mind; stability not to be shaken.
  5. A proof sheet; a trial impression, as from type, taken for correction or examination.
  6. : A process for testing the accuracy of an operation performed. Compare prove, transitive verb, 5.
  7. : Armour of excellent or tried quality, and deemed impenetrable; properly, armour of proof.
  8. A measure of the alcohol content of liquor. Originally, in Britain, 100 proof was defined as 57.1% by volume (not used anymore). In the US, 100 proof means that the alcohol content is 50% of the total volume of the liquid, and thus, absolute alcohol would be 200 proof.



  1. Used in proving or testing; as, a proof load, or proof charge.
  2. Firm or successful in resisting; as, proof against harm; waterproof; bombproof.
    I ... have found thee Proof against all temptation. -Milton.
    This was a good, stout proof article of faith. -Burke.
  3. Being of a certain standard as to strength; -- said of alcoholic liquors.