smear

To spread a greasy or sticky substance untidily over a surface.

"He smeared butter on his crumpet."

A mark or stain made by smearing a greasy or sticky substance.

"There was a smear of jam on the tablecloth."

A false and damaging statement intended to harm someone's reputation.

"The article contained a nasty smear."

To damage someone's reputation by making false or malicious accusations.

"They tried to smear his good name."