Definitions of smut:

• noun:   any fungus of the order Ustilaginales
• noun:   destructive diseases of plants (especially cereal grasses) caused by fungi that produce black powdery masses of spores
• noun:   a black colloidal substance consisting wholly or principally of amorphous carbon and used to make pigments and ink
• noun:   creative activity (writing or pictures or films etc.) of no literary or artistic value other than to stimulate sexual desire
• verb:   stain with a dirty substance, such as soot
• verb:   make obscene

  Example: "This line in the play smuts the entire act"

• verb:   affect with smut or mildew, as of a crop such as corn
• verb:   become affected with smut

  Example: "The corn smutted and could not be eaten"