See blacken in Webster's New World Roget's A-Z Thesaurus II
verb
To make dirty:
befoul, begrime, besmirch, besoil, black, defile, dirty, smudge, smutch, soil, sully. See cleanTo contaminate the reputation of:
befoul, besmear, besmirch, bespatter, cloud, denigrate, dirty, smear, smudge, smut, soil, spatter, stain, sully, taint, tarnish. Idioms: give a black eye to, sling (or throw) mud on. See attack, clean
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