Other forms: maligned; maligning; maligns
If you malign someone, you badmouth them — just like the jilted girlfriend who tells the whole school her ex has bad breath and head lice.
When you habitually malign people, you risk being described as "a malign influence" — in this case, malign is an adjective that describes a harmful or even evil person or thing. Whichever way you use the word, its connection to wickedness can be found in its Latin root, malignus, "wicked or bad-natured," which combines male, or "badly" and -gnus, "born."