proof

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

(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.

The quality or state of having been proved or tried; firmness or hardness which resists impression, or does not yield to force; impenetrability of physical bodies.

(obsolete) Experience of something.

(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.

(numismatics) A limited-run high-quality strike of a particular coin, originally as a test run, although nowadays mostly for collectors' sets.

(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 (no longer used). In the US, 100 proof means that the alcohol content is 50% of the total volume of the liquid; thus, absolute alcohol would be 200 proof.