Synonyms for Denigrate (same or very similar meaning)
WordNet sense 1 (cause to seem less serious; play down):
belittle, derogate, minimize, derogateWordNet sense 2 (charge falsely or with malicious intent; attack the good name and reputation of someone):
besmirch, calumniate, defame, slander, smear, smirch, sully, asperseFrom the ODE community, based on WordNetadd/edit