Libelling is a word that refers to the act of defaming or slandering someone. There are several synonyms for this word that can be used depending on the context and situation. Some of the common synonyms for libelling include maligning, smearing, slandering, defaming, vilifying, discrediting, and derogating. All of these synonyms refer to the act of making false or damaging statements about someone, either in spoken or written form, with the intention of harming their reputation. It is important to use these words carefully and only in situations where it is appropriate, as the consequences of libelling someone can be severe.