To make dirty; soil. See Synonyms at contaminate.(verb-transitive)
To cast aspersions upon; speak badly of.(verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "befoul" in a sentence
"The teabagger trolls that befoul this blog are Klansmen."
"He experienced the gall of bitter suffering under a brutal prison regime but did not let spiritual bitterness befoul his soul."
"Jwest will be the first to throw a hissy fit and befoul his panties after his favorite Starbucks raises their prices 200%."