noun \ˈprüf\

: something which shows that something else is true or correct

: an act or process of showing that something is true

mathematics : a test which shows that a calculation is correct

Full Definition of PROOF

a :  the cogency of evidence that compels acceptance by the mind of a truth or a fact
b :  the process or an instance of establishing the validity of a statement especially by derivation from other statements in accordance with principles of reasoning
obsolete :  experience
:  something that induces certainty or establishes validity
archaic :  the quality or state of having been tested or tried; especially :  unyielding hardness
:  evidence operating to determine the finding or judgment of a tribunal
a plural proofs or proof :  a copy (as of typeset text) made for examination or correction
b :  a test impression of an engraving, etching, or lithograph
c :  a coin that is struck from a highly polished die on a polished planchet, is not intended for circulation, and sometimes differs in metallic content from coins of identical design struck for circulation
d :  a test photographic print made from a negative
:  a test applied to articles or substances to determine whether they are of standard or satisfactory quality
a :  the minimum alcoholic strength of proof spirit
b :  strength with reference to the standard for proof spirit; specifically :  alcoholic strength indicated by a number that is twice the percent by volume of alcohol present <whiskey of 90 proof is 45 percent alcohol>

Examples of PROOF

  1. The document was proof that her story was true.
  2. He claims that he was home when the murder was committed, but he has no proof.
  3. The proof shows that the theorem is true.

Origin of PROOF

Middle English prof, prove, alteration of preve, from Anglo-French preove, from Late Latin proba, from Latin probare to prove — more at prove
First Known Use: 13th century

Other Logic Terms

a posteriori, connotation, corollary, inference, mutually exclusive, paradox, postulate, syllogism

Rhymes with PROOF



: designed or made to prevent or protect against something harmful

Full Definition of PROOF

:  able to resist or repel <boots that were…proof against cold and wet — Robertson Davies> —often used in combination <windproof>
:  used in proving or testing or as a standard of comparison
:  of standard strength or quality or alcoholic content

First Known Use of PROOF


Other Alcoholic Beverage Terms

finish, gimlet, mull, sake, setup, sommelier, syllabub, vintner, wassail



Definition of PROOF

transitive verb
a :  to make or take a proof or test of
b :  proofread
:  to give a resistant quality to
:  to activate (yeast) by mixing with water and sometimes sugar or milk
proof·er noun

Examples of PROOF

  1. She proofed the story carefully.

First Known Use of PROOF


Other Printing Terms

epigraph, errata, leader, mechanical, notch, tittle, underscore, widow


noun    (Concise Encyclopedia)

In logic and mathematics, an argument that establishes a proposition's validity. Formally, it is a finite sequence of formulas generated according to accepted rules. Each formula either is an axiom or is derived from a previously established theorem, and the last formula is the statement that is to be proven. The essence of deductive reasoning (see deduction), this is the basis of Euclidean geometry and all scientific methods inspired by it. An alternative form of proof, called mathematical induction, applies to propositions defined through processes based on the counting numbers. If the proposition holds for n = 1 and can be shown to hold for n = k + 1 whenever n = k (a constant) is also true, then it holds for all values of n. An example is the assertion that the sum of the first n counting numbers is n(n + 1)/2.


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