Smut n.
 1. Foul matter, like soot or coal dust; also, a spot or soil made by such matter.
 2. Mining Bad, soft coal, containing much earthy matter, found in the immediate locality of faults.
 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.
 4. Obscene language; ribaldry; obscenity.
    He does not stand upon decency . . . but will talk smut, though a priest and his mother be in the room.   --Addison.
 Smut mill, a machine for cleansing grain from smut.


 Ustilago maydis
      n : a common smut attacking Indian corn causing grayish white
          swellings that rupture to expose a black spore mass [syn:
           boil smut]