to water down, dumb down or especially weaken, particularly in the context of weapons in video games. (A term derived from the foam brand of toys, which are generally made safe for play. The term compares the subject to foam.)
The lightning spell was pretty powerful before they nerfed it.
1. Nerf is a term that means to be rendered ineffective or less effective by a change in the rules or game system. The term nerf is based on Non-Expanding Recreational Foam, a substance used to make toy weapons. 2. Turn a real weapon into a toy weapon
(Bilgisayar) In video gaming a nerf is a change to a game that reduces the desirability or effectiveness of a particular game element. The term is also used as a verb for the act of making such a change.The opposite of nerf is buff