The Collaborative International Dictionary of English v.0.48:

Smut \Smut\, n. [Akin to Sw. smuts, Dan. smuds, MHG. smuz, G.
   schmutz, D. smet a spot or stain, smoddig, smodsig,
   smodderig, dirty, smodderen to smut; and probably to E.
   smite. See Smite, v. t., and cf. Smitt, Smutch.]
   1. Foul matter, like soot or coal dust; also, a spot or soil
      made by such matter.
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   2. (Mining) Bad, soft coal, containing much earthy matter,
      found in the immediate locality of faults.
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   3. (Bot.) An infection of cereal grains producing a swelling
      which is at length resolved into a powdery sooty mass. It
      is caused by parasitic fungi of the genus Ustilago.
      Ustilago segetum, or Ustilago Carbo, is the commonest
      kind; that of Indian corn is Ustilago maydis.
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   4. Obscene language; ribaldry; obscenity.
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            He does not stand upon decency . . . but will talk
            smut, though a priest and his mother be in the room.
                                                  --Addison.
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   Smut mill, a machine for cleansing grain from smut.
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The Collaborative International Dictionary of English v.0.48:

Dust \Dust\ (d[u^]st), n. [AS. dust; cf. LG. dust, D. duist meal
   dust, OD. doest, donst, and G. dunst vapor, OHG. tunist,
   dunist, a blowing, wind, Icel. dust dust, Dan. dyst mill
   dust; perh. akin to L. fumus smoke, E. fume. [root]71.]
   1. Fine, dry particles of earth or other matter, so
      comminuted that they may be raised and wafted by the wind;
      that which is crumbled to minute portions; fine powder;
      as, clouds of dust; bone dust.
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            Dust thou art, and unto dust shalt thou return.
                                                  --Gen. iii.
                                                  19.
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            Stop! -- for thy tread is on an empire's dust.
                                                  --Byron.
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   2. A single particle of earth or other matter. [R.] "To touch
      a dust of England's ground." --Shak.
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   3. The earth, as the resting place of the dead.
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            For now shall sleep in the dust.      --Job vii. 21.
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   4. The earthy remains of bodies once alive; the remains of
      the human body.
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            And you may carve a shrine about my dust.
                                                  --Tennyson.
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   5. Figuratively, a worthless thing.
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            And by the merit of vile gold, dross, dust. --Shak.
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   6. Figuratively, a low or mean condition.
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            [God] raiseth up the poor out of the dust. --1 Sam.
                                                  ii. 8.
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   7. Gold dust; hence: (Slang) Coined money; cash.
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   Down with the dust, deposit the cash; pay down the money.
      [Slang] "My lord, quoth the king, presently deposit your
      hundred pounds in gold, or else no going hence all the
      days of your life. . . . The Abbot down with his dust, and
      glad he escaped so, returned to Reading." --Fuller.

   Dust brand (Bot.), a fungous plant (Ustilago Carbo); --
      called also smut.

   Gold dust, fine particles of gold, such as are obtained in
      placer mining; -- often used as money, being transferred
      by weight.

   In dust and ashes. See under Ashes.

   To bite the dust. See under Bite, v. t.

   To raise dust, or

   To kick up dust, to make a commotion. [Colloq.]

   To throw dust in one's eyes, to mislead; to deceive.
      [Colloq.]
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