Synonyms for Blot (same or very similar meaning)
WordNet sense 1 (a blemish made by dirt):
daub, slur, smear, smirch, smudge, spotWordNet sense 2 (make a spot or mark onto):
blob, fleckWordNet sense 3 (an act that brings discredit to the person who does it):
stainFrom the ODE community, based on WordNetadd/edit