1. Used in proving or testing; as, a
proof load, or proof charge.
2. Firm or successful in resisting; as,
proof against harm; waterproof;
I . . . have found thee Milton.
Proof against all temptation.
This was a good, stout proof article of
3. Being of a certain standard as to strength;
-- said of alcoholic liquors.
Proof charge (Firearms), a charge of
powder and ball, greater than the service charge, fired in an arm, as
a gun or cannon, to test its strength. -- Proof
impression. See under Impression. --
Proof load (Engin.), the greatest load
than can be applied to a piece, as a beam, column, etc., without
straining the piece beyond the elastic limit. -- Proof
sheet. See Proof, n., 5. -
- Proof spirit (Chem.), a strong
distilled liquor, or mixture of alcohol and water, containing not less
than a standard amount of alcohol. In the United States "proof spirit
is defined by law to be that mixture of alcohol and water which
contains one half of its volume of alcohol, the alcohol when at a
temperature of 60° Fahrenheit being of specific gravity 0.7939
referred to water at its maximum density as unity. Proof spirit has at
60° Fahrenheit a specific gravity of 0.93353, 100 parts by volume
of the same consisting of 50 parts of absolute alcohol and 53.71 parts
of water," the apparent excess of water being due to contraction of
the liquids on mixture. In England proof spirit is defined by Act 58,
George III., to be such as shall at a temperature of 51°
Fahrenheit weigh exactly the 12⁄13 part of an equal measure of
distilled water. This contains 49.3 per cent by weight, or 57.09 by
volume, of alcohol. Stronger spirits, as those of about 60, 70, and 80
per cent of alcohol, are sometimes called second, third,
and fourth proof spirits respectively. -- Proof
staff, a straight-edge used by millers to test the
flatness of a stone. -- Proof stick (Sugar
Manuf.), a rod in the side of a vacuum pan, for testing the
consistency of the sirup. -- Proof text, a
passage of Scripture used to prove a doctrine.
Proof (?), n. [OF. prove,
proeve, F. preuve, fr. L. proba, fr.
probare to prove. See Prove.]
1. Any effort, process, or operation designed
to establish or discover a fact or truth; an act of testing; a test; a
For whatsoever mother wit or art Spenser.
Could work, he put in proof.
You shall have many proofs to show your
Formerly, a very rude mode of ascertaining the strength
of spirits was practiced, called the proof.
2. That degree of evidence which convinces the
mind of any truth or fact, and produces belief; a test by facts or
arguments that induce, or tend to induce, certainty of the judgment;
conclusive evidence; demonstration.
I'll have some proof.
It is no proof of a man's understanding to be
able to confirm whatever he pleases. Emerson.
☞ Properly speaking, proof is the effect or result of
evidence, evidence is the medium of proof. Cf. Demonstration,
3. The quality or state of having been proved
or tried; firmness or hardness that resists impression, or does not
yield to force; impenetrability of physical bodies.
4. Firmness of mind; stability not to be
5. (Print.) A trial impression, as from
type, taken for correction or examination; -- called also proof
6. (Math.) A process for testing the
accuracy of an operation performed. Cf. Prove, v.
7. Armor of excellent or tried quality, and
deemed impenetrable; properly, armor of proof. [Obs.]
Artist's proof, a very early proof impression
of an engraving, or the like; -- often distinguished by the artist's
signature. -- Proof reader, one who reads,
and marks correction in, proofs. See def. 5, above.
Syn. -- Testimony; evidence; reason; argument; trial;
demonstration. See Testimony.