Verb (5-dan, す, transitive)
1. to pollute; to contaminate; to soil; to make dirty; to stain
そのハンカチを汚さないで!Don't get that handkerchief dirty!
2. to disgrace; to dishonour; to dishonor; to defile
esp. けがす
だが勝負を汚すような真似はすんな。But don't do anything that would taint the match.