The Collaborative International Dictionary of English v.0.48:

But \But\ (b[u^]t), prep., adv. & conj. [OE. bute, buten, AS.
   b[=u]tan, without, on the outside, except, besides; pref. be-
   + [=u]tan outward, without, fr. [=u]t out. Primarily,
   b[=u]tan, as well as [=u]t, is an adverb. [root]198. See
   By, Out; cf. About.]
   1. Except with; unless with; without. [Obs.]
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            So insolent that he could not go but either spurning
            equals or trampling on his inferiors. --Fuller.
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            Touch not the cat but a glove.        --Motto of the
                                                  Mackintoshes.
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   2. Except; besides; save.
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            Who can it be, ye gods! but perjured Lycon? --E.
                                                  Smith.
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   Note: In this sense, but is often used with other particles;
         as, but for, without, had it not been for. "Uncreated
         but for love divine." --Young.
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   3. Excepting or excluding the fact that; save that; were it
      not that; unless; -- elliptical, for but that.
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            And but my noble Moor is true of mind . . . it were
            enough to put him to ill thinking.    --Shak.
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   4. Otherwise than that; that not; -- commonly, after a
      negative, with that.
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            It cannot be but nature hath some director, of
            infinite power, to guide her in all her ways.
                                                  --Hooker.
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            There is no question but the king of Spain will
            reform most of the abuses.            --Addison.
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   5. Only; solely; merely.
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            Observe but how their own principles combat one
            another.                              --Milton.
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            If they kill us, we shall but die.    --2 Kings vii.
                                                  4.
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            A formidable man but to his friends.  --Dryden.
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   6. On the contrary; on the other hand; only; yet; still;
      however; nevertheless; more; further; -- as connective of
      sentences or clauses of a sentence, in a sense more or
      less exceptive or adversative; as, the House of
      Representatives passed the bill, but the Senate dissented;
      our wants are many, but quite of another kind.
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            Now abideth faith hope, charity, these three; but
            the greatest of these is charity.     --1 Cor. xiii.
                                                  13.
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            When pride cometh, then cometh shame; but with the
            lowly is wisdom.                      --Prov. xi. 2.
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   All but. See under All.

   But and if, but if; an attempt on the part of King James's
      translators of the Bible to express the conjunctive and
      adversative force of the Greek ?.
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            But and if that servant say in his heart, My lord
            delayeth his coming; . . . the lord of that servant
            will come in a day when he looketh not for him.
                                                  --Luke xii.
                                                  45, 46.
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   But if, unless. [Obs.] --Chaucer.
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            But this I read, that but if remedy
            Thou her afford, full shortly I her dead shall see.
                                                  --Spenser.
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   Syn: But, However, Still.

   Usage: These conjunctions mark opposition in passing from one
          thought or topic to another. But marks the opposition
          with a medium degree of strength; as, this is not
          winter, but it is almost as cold; he requested my
          assistance, but I shall not aid him at present.
          However is weaker, and throws the opposition (as it
          were) into the background; as, this is not winter; it
          is, however, almost as cold; he required my
          assistance; at present, however, I shall not afford
          him aid. The plan, however, is still under
          consideration, and may yet be adopted. Still is
          stronger than but, and marks the opposition more
          emphatically; as, your arguments are weighty; still
          they do not convince me. See Except, However.
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   Note: "The chief error with but is to use it where and is
         enough; an error springing from the tendency to use
         strong words without sufficient occasion." --Bain.
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The Collaborative International Dictionary of English v.0.48:

But \But\, n. [Cf. But, prep., adv. & conj.]
   The outer apartment or kitchen of a two-roomed house; --
   opposed to ben, the inner room. [Scot.]
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The Collaborative International Dictionary of English v.0.48:

But \But\, n. [See 1st But.]
   1. A limit; a boundary.
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   2. The end; esp. the larger or thicker end, or the blunt, in
      distinction from the sharp, end. Now disused in this
      sense, being replaced by butt[2]. See 1st Butt.
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   But end, the larger or thicker end; as, the but end of a
      log; the but end of a musket. See Butt, n.
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The Collaborative International Dictionary of English v.0.48:

But \But\, v. i. [imp. & p. p. Butted; p. pr. & vb. n.
   Butting.]
   See Butt, v., and Abut, v.
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The Collaborative International Dictionary of English v.0.48:

Butt \Butt\, But \But\, n. [F. but butt, aim (cf. butte knoll),
   or bout, OF. bot, end, extremity, fr. boter, buter, to push,
   butt, strike, F. bouter; of German origin; cf. OHG. b[=o]zan,
   akin to E. beat. See Beat, v. t.]
   1. A limit; a bound; a goal; the extreme bound; the end.
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            Here is my journey's end, here my butt
            And very sea mark of my utmost sail.  --Shak.
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   Note: As applied to land, the word is nearly synonymous with
         mete, and signifies properly the end line or boundary;
         the abuttal.
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   2. The larger or thicker end of anything; the blunt end, in
      distinction from the sharp end; as, the butt of a rifle.
      Formerly also spelled but. See 2nd but, n. sense 2.
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   3. A mark to be shot at; a target. --Sir W. Scott.
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            The groom his fellow groom at butts defies,
            And bends his bow, and levels with his eyes.
                                                  --Dryden.
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   4. A person at whom ridicule, jest, or contempt is directed;
      as, the butt of the company.
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            I played a sentence or two at my butt, which I
            thought very smart.                   --Addison.
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   5. A push, thrust, or sudden blow, given by the head of an
      animal; as, the butt of a ram.
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   6. A thrust in fencing.
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            To prove who gave the fairer butt,
            John shows the chalk on Robert's coat. --Prior.
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   7. A piece of land left unplowed at the end of a field.
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            The hay was growing upon headlands and butts in
            cornfields.                           --Burrill.
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   8. (Mech.)
      (a) A joint where the ends of two objects come squarely
          together without scarfing or chamfering; -- also
          called butt joint.
      (b) The end of a connecting rod or other like piece, to
          which the boxing is attached by the strap, cotter, and
          gib.
      (c) The portion of a half-coupling fastened to the end of
          a hose.
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   9. (Shipbuilding) The joint where two planks in a strake
      meet.
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   10. (Carp.) A kind of hinge used in hanging doors, etc.; --
       so named because fastened on the edge of the door, which
       butts against the casing, instead of on its face, like
       the strap hinge; also called butt hinge.
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   11. (Leather Trade) The thickest and stoutest part of tanned
       oxhides, used for soles of boots, harness, trunks.
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   12. The hut or shelter of the person who attends to the
       targets in rifle practice.
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   13. The buttocks; as, get up off your butt and get to work;
       -- used as a euphemism, less objectionable than ass.
       [slang]

   Syn: ass, rear end, derriere, behind, rump, heinie.
        [PJC]

   Butt chain (Saddlery), a short chain attached to the end of
      a tug.

   Butt end. The thicker end of anything. See But end, under
      2d But.
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            Amen; and make me die a good old man!
            That's the butt end of a mother's blessing. --Shak.
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   A butt's length, the ordinary distance from the place of
      shooting to the butt, or mark.

   Butts and bounds (Conveyancing), abuttals and boundaries.
      In lands of the ordinary rectangular shape, butts are the
      lines at the ends (F. bouts), and bounds are those on the
      sides, or sidings, as they were formerly termed.
      --Burrill.

   Bead and butt. See under Bead.

   Butt and butt, joining end to end without overlapping, as
      planks.

   Butt weld (Mech.), a butt joint, made by welding together
      the flat ends, or edges, of a piece of iron or steel, or
      of separate pieces, without having them overlap. See
      Weld.

   Full butt, headfirst with full force. [Colloq.] "The
      corporal . . . ran full butt at the lieutenant."
      --Marryat.
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The Collaborative International Dictionary of English v.0.48:

Butt \Butt\, v. i. [imp. & p. p. Butted; p. pr. & vb. n.
   Butting.] [OE. butten, OF. boter to push, F. bouter. See
   Butt an end, and cf. Boutade.]
   1. To join at the butt, end, or outward extremity; to
      terminate; to be bounded; to abut. [Written also but.]
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            And Barnsdale there doth butt on Don's well-watered
            ground.                               --Drayton.
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   2. To thrust the head forward; to strike by thrusting the
      head forward, as an ox or a ram. [See Butt, n.]
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            A snow-white steer before thine altar led,
            Butts with his threatening brows.     --Dryden.
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WordNet (r) 3.0 (2006):

but
    adv 1: and nothing more; "I was merely asking"; "it is simply a
           matter of time"; "just a scratch"; "he was only a child";
           "hopes that last but a moment" [syn: merely, simply,
           just, only, but]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "but":
   after all, again, albeit, all the same, alone, although,
   aside from, at all events, at any rate, bar, barring, besides,
   entirely, even, even so, except, except that, excepting, excluding,
   exclusively, for all that, howbeit, however, if not, in any case,
   in any event, just the same, merely, nevertheless, nonetheless,
   notwithstanding, only, outside of, rather, save, saving, simply,
   solely, still, though, unless, unless that, were it not, when,
   without, yet