Harmful or evil in intent or effect
The opiate of Zeus’s daughter bore this canny power. It had been supplied her by Polydmnia, mistress of Lord Thon, in Egypt, where the rich plantations grow herbs of all kinds, maleficent and healthful; and no one else knows medicines as they do, Egyptian heirs of Paian, the healing god.–Homer. The Odyssey, book 4.
Here’s another one from my husband, whose reading tastes are slightly more academic than mine. Thanks, Shane!
Definition from OneLook Online Dictionary