The Rice University Neologisms Database

To weaken or disable something. The verb nerf is commonly used among players of multiplayer computer games to denote a change in the rules of the game that weakens an overly powerful weapon or strategy. It is common for developers of multiplayer computer games to alter elements of the game after it has been released in order to make the game more fair. When a weapon is made less powerful, gamers refer to it as having been nerfed as a way of comparing it the brand of harmless Nerf foam toys. This word is almost always used in a gaming context, but my roommate extended this word to be used in the real world. This word is primarily used as a shibboleth to show membership in the culture of gamers.