The Collaborative International Dictionary of English v.0.48:

Proof \Proof\, a.
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   1. Used in proving or testing; as, a proof load, or proof
      charge.
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   2. Firm or successful in resisting; as, proof against harm;
      waterproof; bombproof.
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            I . . . have found thee
            Proof against all temptation.         --Milton.
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            This was a good, stout proof article of faith.
                                                  --Burke.
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   3. Being of a certain standard as to strength; -- said of
      alcoholic liquors.
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   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[deg] Fahrenheit being
      of specific gravity 0.7939 referred to water at its
      maximum density as unity. Proof spirit has at 60[deg]
      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[deg] 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.
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The Collaborative International Dictionary of English v.0.48:

Spirit \Spir"it\, n. [OF. espirit, esperit, F. esprit, L.
   spiritus, from spirare to breathe, to blow. Cf. Conspire,
   Expire, Esprit, Sprite.]
   1. Air set in motion by breathing; breath; hence, sometimes,
      life itself. [Obs.] "All of spirit would deprive."
      --Spenser.
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            The mild air, with season moderate,
            Gently attempered, and disposed eo well,
            That still it breathed foorth sweet spirit.
                                                  --Spenser.
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   2. A rough breathing; an aspirate, as the letter h; also, a
      mark to denote aspiration; a breathing. [Obs.]
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            Be it a letter or spirit, we have great use for it.
                                                  --B. Jonson.
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   3. Life, or living substance, considered independently of
      corporeal existence; an intelligence conceived of apart
      from any physical organization or embodiment; vital
      essence, force, or energy, as distinct from matter.
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   4. The intelligent, immaterial and immortal part of man; the
      soul, in distinction from the body in which it resides;
      the agent or subject of vital and spiritual functions,
      whether spiritual or material.
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            There is a spirit in man; and the inspiration of the
            Almighty giveth them understanding.   --Job xxxii.
                                                  8.
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            As the body without the spirit is dead, so faith
            without works is dead also.           --James ii.
                                                  26.
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            Spirit is a substance wherein thinking, knowing,
            doubting, and a power of moving, do subsist.
                                                  --Locke.
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   5. Specifically, a disembodied soul; the human soul after it
      has left the body.
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            Then shall the dust return to the earth as it was,
            and the spirit shall return unto God who gave it.
                                                  --Eccl. xii.
                                                  7.
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            Ye gentle spirits far away,
            With whom we shared the cup of grace. --Keble.
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   6. Any supernatural being, good or bad; an apparition; a
      specter; a ghost; also, sometimes, a sprite,; a fairy; an
      elf.
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            Whilst young, preserve his tender mind from all
            impressions of spirits and goblins in the dark.
                                                  --Locke.
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   7. Energy, vivacity, ardor, enthusiasm, courage, etc.
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            "Write it then, quickly," replied Bede; and
            summoning all his spirits together, like the last
            blaze of a candle going out, he indited it, and
            expired.                              --Fuller.
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   8. One who is vivacious or lively; one who evinces great
      activity or peculiar characteristics of mind or temper;
      as, a ruling spirit; a schismatic spirit.
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            Such spirits as he desired to please, such would I
            choose for my judges.                 --Dryden.
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   9. Temper or disposition of mind; mental condition or
      disposition; intellectual or moral state; -- often in the
      plural; as, to be cheerful, or in good spirits; to be
      downhearted, or in bad spirits.
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            God has . . . made a spirit of building succeed a
            spirit of pulling down.               --South.
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            A perfect judge will read each work of wit
            With the same spirit that its author writ. --Pope.
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   10. Intent; real meaning; -- opposed to the letter, or to
       formal statement; also, characteristic quality,
       especially such as is derived from the individual genius
       or the personal character; as, the spirit of an
       enterprise, of a document, or the like.
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   11. Tenuous, volatile, airy, or vapory substance, possessed
       of active qualities.
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             All bodies have spirits . . . within them. --Bacon.
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   12. Any liquid produced by distillation; especially, alcohol,
       the spirits, or spirit, of wine (it having been first
       distilled from wine): -- often in the plural.
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   13. pl. Rum, whisky, brandy, gin, and other distilled liquors
       having much alcohol, in distinction from wine and malt
       liquors.
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   14. (Med.) A solution in alcohol of a volatile principle. Cf.
       Tincture. --U. S. Disp.
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   15. (Alchemy) Any one of the four substances, sulphur, sal
       ammoniac, quicksilver, or arsenic (or, according to some,
       orpiment).
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             The four spirits and the bodies seven. --Chaucer.
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   16. (Dyeing) Stannic chloride. See under Stannic.
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   Note: Spirit is sometimes joined with other words, forming
         compounds, generally of obvious signification; as,
         spirit-moving, spirit-searching, spirit-stirring, etc.
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   Astral spirits, Familiar spirits, etc. See under
      Astral, Familiar, etc.

   Animal spirits.
       (a) (Physiol.) The fluid which at one time was supposed
           to circulate through the nerves and was regarded as
           the agent of sensation and motion; -- called also the
           nervous fluid, or nervous principle.
       (b) Physical health and energy; frolicsomeness;
           sportiveness.

   Ardent spirits, strong alcoholic liquors, as brandy, rum,
      whisky, etc., obtained by distillation.

   Holy Spirit, or The Spirit (Theol.), the Spirit of God,
      or the third person of the Trinity; the Holy Ghost. The
      spirit also signifies the human spirit as influenced or
      animated by the Divine Spirit.

   Proof spirit. (Chem.) See under Proof.

   Rectified spirit (Chem.), spirit rendered purer or more
      concentrated by redistillation, so as to increase the
      percentage of absolute alcohol.

   Spirit butterfly (Zool.), any one of numerous species of
      delicate butterflies of tropical America belonging to the
      genus Ithomia. The wings are gauzy and nearly destitute
      of scales.

   Spirit duck. (Zool.)
       (a) The buffle-headed duck.
       (b) The golden-eye.

   Spirit lamp (Art), a lamp in which alcohol or methylated
      spirit is burned.

   Spirit level. See under Level.

   Spirit of hartshorn. (Old Chem.) See under Hartshorn.

   Spirit of Mindererus (Med.), an aqueous solution of acetate
      of ammonium; -- named after R. Minderer, physician of
      Augsburg.

   Spirit of nitrous ether (Med. Chem.), a pale yellow liquid,
      of a sweetish taste and a pleasant ethereal odor. It is
      obtained by the distillation of alcohol with nitric and
      sulphuric acids, and consists essentially of ethyl nitrite
      with a little acetic aldehyde. It is used as a
      diaphoretic, diuretic, antispasmodic, etc. Called also
      sweet spirit of niter.

   Spirit of salt (Chem.), hydrochloric acid; -- so called
      because obtained from salt and sulphuric acid. [Obs.]

   Spirit of sense, the utmost refinement of sensation. [Obs.]
      --Shak.

   Spirits of turpentine, or Spirit of turpentine (Chem.),
      rectified oil of turpentine, a transparent, colorless,
      volatile, and very inflammable liquid, distilled from the
      turpentine of the various species of pine; camphine. It is
      commonly used to remove paint from surfaces, or to dissole
      oil-based paint. See Camphine.

   Spirit of vitriol (Chem.), sulphuric acid; -- so called
      because formerly obtained by the distillation of green
      vitriol. [Obs.]

   Spirit of vitriolic ether (Chem.) ethyl ether; -- often but
      incorrectly called sulphuric ether. See Ether. [Obs.]


   Spirits of wine, or Spirit of wine (Chem.), alcohol; --
      so called because formerly obtained by the distillation of
      wine.

   Spirit rapper, one who practices spirit rapping; a "medium"
      so called.

   Spirit rapping, an alleged form of communication with the
      spirits of the dead by raps. See Spiritualism, 3.

   Sweet spirit of niter. See Spirit of nitrous ether,
      above.
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   Syn: Life; ardor; energy; fire; courage; animatioon;
        cheerfulness; vivacity; enterprise.
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WordNet (r) 3.0 (2006):

proof spirit
    n 1: a mixture containing half alcohol by volume at 60 degrees
         Fahrenheit