Proof

From Middle English proof, from Old French prove, from Late Latin proba ("a proof"), from Latin probare ("to prove"); see prove.

Full definition of proof

(countable and uncountable; plural proofs)

(countable) An effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.

1591, Edmund Spenser, Prosopopoia: or, Mother Hubbard's Tale, later also published in , Humorous Poems,But the false Fox most kindly played his part,For whatsoever mother-wit or artCould work he put in proof. No practice sly,No counterpoint of cunning policy,No reach, no breach, that might him profit bring.But he the same did to his purpose wring.
c. 1633, John Ford (dramatist), , Act 1, Scene 1,France I more praise and love; you are, my lord,Yourself for horsemanship much famed; and thereYou shall have many proofs to shew your skill.
1831, Thomas Thomson, A System of Chemistry of Inorganic Bodies, Volume 2,A given quantity of the spirits was poured upon a quantity of gunpowder in a dish and set on fire. If at the end of the combustion, the gunpowder continued dry enough, it took fire and exploded; but if it had been wetted by the water in the spirits, the flame of the alcohol went out without setting the powder on fire. This was called the proof.

(uncountable) 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.

c.1603, William Shakespeare, ,I'll have some proof.
1841, Ralph Waldo Emerson, in Essays: First Series,It was a grand sentence of Emanuel Swedenborg, which would alone indicate the greatness of that man's perception, â€” "It is no proof of a man's understanding to be able to confirm whatever he pleases; but to be able to discern that what is true is true, and that what is false is false, this is the mark and character of intelligence."
1990 October 16, Paul Simon, "Proof" in , ,Faith, faith is an island in the setting sunBut proof, yesProof is the bottom line for everyone

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.
(obsolete) Experience of something.

1590, Edmund Spenser, The Faerie Queene, III.1:But the chaste damzell, that had never priefe
Of such malengine and fine forgerye,
Did easely beleeve her strong extremitye.

(uncountable, obsolete) Firmness of mind; stability not to be shaken.
(countable, printing) A proof sheet; a trial impression, as from type, taken for correction or examination.
(countable, logic, mathematics) A sequence of statements consisting of axioms, assumptions, statements already demonstrated in another proof, and statements that logically follow from previous statements in the sequence, and which concludes with a statement that is the object of the proof.
(countable, mathematics) A process for testing the accuracy of an operation performed. Compare prove, transitive verb, 5.
(obsolete) Armour of excellent or tried quality, and deemed impenetrable; properly, armour of proof.
(US) 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.

1671, John Milton, , 1820, Dr Aiken (biographies), Select Works of the British Poets, page 125,And opportunity I here have had
To try thee, sift thee, and confess have found thee
Proof against all temptation as a rock
Of adamant, and, as a centre, firm :
1790, Edmund Burke, Reflections on the Revolution in France, 1803, The Works of The Right Honourable Edmund Burke, Volume 5, page426,This was a good, Å¿tout proof article of faith, pronounced under an anathema, by the venerable fathers of this philoÅ¿ophick Å¿ynod.