noun

the action of damaging the good reputation of someone; slander or libel.

she sued him for defamation

libel,slander,character assassination,defamation of character,calumny,vilification,traducement,obloquy,scandal,scandalmongering,malicious gossip,tittle-tattle,backbiting,aspersions,muckraking,abuse,malediction,disparagement,denigration,detraction,derogation,opprobrium,censure,criticism,smear,slur,lie,false report,smear campaign,rumour,insult,mud-slinging,slagging-off,knocking,bitching,bad-mouthing,contumely