Defame

[Sonia]

To harm or destroy the good fame or reputation of; to
disgrace; especially, to speak evil of maliciously; to dishonor by
slanderous reports; to calumniate; to asperse.

[PussyCat]

Damage the good reputation of (someone); slander or libel.

[Julene]

verb
pronounced (dǝ [faim])

To ruin the reputation of; [libel] (written) or [slander] (verbal).

[Tariq Zaki]

to damage the reputation of a person or group by saying or writing bad things about them that are not true: