1911 Encyclopædia Britannica/Proof

PROOF (in M. Eng. preove, proeve, preve, &c., from O. Fr. prueve, proeve, &c., mod. preove, Late. Lat. proba, probare, to prove, to test the goodness of anything, probus, good), a word of which the two main branches are derived from those of "to prove," viz. to show to be true, to test, to try. Of the first division the chief meanings are: that which establishes the truth of a fact or the belief in the truth, demonstration, for the nature of which see. In law "proof" is the general term for the establishment of the material facts in issue in a particular case by proper legal means to the satisfaction of the court (see ); specifically, documents so attested as to form legal evidence, written copies of what a witness is prepared to support on oath, and the evidence of any case in the court records are all termed "proofs." In Scots law the term is used of a trial before a judge alone as opposed to trial by jury. From the general sense of examination, trial or assay derived from "to prove," to test the quality of anything, "proof" is used of that which has succeeded in standing a trial or test; the commonest form in which this use appears is as a compound adjective, thus materials are said to be "waterproof," "armour-" "bullet-proof," and the like. The principal other uses are for a standard of strength for spirit (see and ) for a trial impression, in printing, on which corrections and additions can be made (see article ) and, in engraving and etching, for one of a limited number of impressions made before the ordinary issue is printed. In the earlier history of engraving a "proof" was an impression during the process of printing made for the artist's inspection, approval or correction, whence its name. In the modern use of the term, where the impression has been taken before the inscription has been added to the plate, it is called a "proof before letter."

In bookbinding, some of the shorter or narrower leaves are left with rough edges, "uncropped," to show that the book has not been "cut," these are styled "proofs."