Webster’s Revised Unabridged Dictionary · 1913
Denigrate
Den′i·grate (dĕn′ĭ·grāt), v. t. [L. denigrare; de- + nigrare to blacken, niger black.] 1. To blacken thoroughly; to make very black. Boyle.
2. Fig.: To blacken or sully; to defame. [R.]
To denigrate the memory of Voltaire. Morley.