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Synonyms for Blot (same or very similar meaning)

WordNet sense 1 (a blemish made by dirt):
daub, slur, smear, smirch, smudge, spot

WordNet sense 2 (make a spot or mark onto):
blob, fleck

WordNet sense 3 (an act that brings discredit to the person who does it):

From the ODE community, based on WordNetadd/edit