Badmouthing is an act of speaking derogatory and negative comments about someone or something. There are several synonyms for the word, including slandering, defaming, vilifying, disparaging, maligning, decrying, denigrating, and smearing. Slandering refers to making false and damaging statements about someone with the intention of harming their reputation. Defaming is similar to slandering, but it involves making such statements publicly. Vilifying refers to denouncing and criticizing someone harshly. Disparaging is a term used to express a negative opinion regarding someone or something. Maligning means to speak ill of someone with the intention of causing harm. Decrying refers to expressing strong disapproval of someone or something. Denigrating refers to attacking someone's reputation by belittling them. Smearing means to spread false and damaging information about someone or something.