denigrate v.– to say critical/unfair things about someone; to make something/someone seem less valuable
denigrate (v.) 1520s, from Latin denigratus, past participle of denigrare “to blacken, defame,” from de- “completely” (see de-) + nigr-, stem of niger “black” (see Negro). which is of unknown origin. “Apparently disused in 18th c. and revived in 19th c.” [OED]. Related: Denigrated; denigrating.