ETYM Akin to Swed. smuts, Dan. smuds, Mid. High Germ. smuz, German schmutz, Dutch smet a spot or stain, smoddig, smodsig, smodderig, dirty, smodderen to smut; and probably to Eng. smite. Related to Smite, Smitt, Smutch.
1. Any fungus of the order Usrilaginales; SYN. smut fungus.
2. Destructive diseases of plants (especially cereal grasses) caused by fungi that produce black powdery masses of spores.
In botany, any parasitic fungus of the order Ustilaginales, which infects flowering plants, particularly cereal grasses.

1. To affect with smut or mildew, as of a crop such as corn.
2. To become affected with smut, as of corn.
3. To stain with a dirty substance, such as soot.