1664, "black mark, stain," from verb smutten "debase, defile" (early 15c.), cognate with M.H.G. smotzen "make dirty," from W.Gmc. *smutt- (cf. M.H.G. smuz "grease, dirt," Ger. Schmutz "dirt," Ger. schmutzen "to make dirty"). The meaning "indecent or obscene language" is first attested 1668 (implied in smutty).
Any of various bacidiomycete fungi that are parasitic on plants and are distinguished by the black, powdery masses of spores that appear as sooty smudges on the affected plant parts. Smuts are parasitic chiefly on cereal grasses like corn and wheat and can cause enormous damage to crops.
Any of the various plant diseases caused by smuts, such as corn smut.