1 a dirty mark made by spreading a substance across sth 污点；污渍

2 something that is not true that is said or written about an important person and that is intended to damage people's opinion about him/her, especially in politics （对重要人物的）诽谤，诋毁，抹黑（尤指在政界）: He was the victim of a smear campaign. 他是一场诽谤运动的受害者。