denigration (n.)

early 15c., denigracioun, "act of making or becoming black, darkening, discoloration," from Late Latin denigrationem (nominative denigratio), noun of action from past-participle stem of Latin denigrare "to blacken; to defame," from de-"completely" (see de-) + nigr-, stem of niger "black," which is of unknown origin. Figurative sense "blackening of character or reputation" is by 1868.