mark, stigma, brand, stain -- (a symbol of disgrace or infamy; "And the Lord set a mark upon Cain"--Genesis)
blot, smear, smirch, spot, stain -- (an act that brings discredit to the person who does it; "he made a huge blot on his copybook")
Overview of verb stain
The verb stain has 4 senses
stain -- (color with a liquid dye or tint; "Stain this table a beautiful walnut color"; "people knew how to stain glass a beautiful blue in the middle ages")
stain -- (produce or leave stains; "Red wine stains the table cloth")
tarnish, stain, maculate, sully, defile -- (make dirty or spotty, as by exposure to air; also used metaphorically; "The silver was tarnished by the long exposure to the air"; "Her reputation was sullied after the affair with a married man")
stain -- (color for microscopic study; "The laboratory worker dyed the specimen")