The Collaborative International Dictionary of English v.0.48:

Smut \Smut\, v. t. [imp. & p. p. Smutted; p. pr. & vb. n.
   Smutting.]
   1. To stain or mark with smut; to blacken with coal, soot, or
      other dirty substance.
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   2. To taint with mildew, as grain. --Bacon.
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   3. To blacken; to sully or taint; to tarnish.
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   4. To clear of smut; as, to smut grain for the mill.
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