* Slander: Spoken defamation.
* Libel: Written defamation.
* Defamation: Any false statement that harms a person's reputation.
* Vilification: The act of speaking or writing about someone in a very harsh and abusive way.
* Smear campaign: A planned effort to damage someone's reputation through negative publicity.
* Detraction: The act of saying negative things about someone, especially in a subtle or indirect way.
* Aspersion: A damaging or false accusation.
* Backbiting: Talking badly about someone behind their back.
* Scandalmongering: Spreading rumors and gossip that damage someone's reputation.
* Character assassination: The deliberate attempt to destroy someone's reputation.
The specific synonym you choose will depend on the context and the nuance you want to convey.