To nerf something is to reduce its power or effectiveness in a game update, and a nerf is such a reduction. Nerfs target weapons, abilities, characters, or strategies judged too strong for the health of the game.
The word comes from Nerf toys, whose foam darts hurt no one. Players adopted it for changes that made a fearsome weapon feel foam soft by comparison. A nerf can cut damage, raise a cooldown, shrink a hitbox, reduce range, or add a cost, and it can also be indirect: strengthening a counter, or fixing a bug that a strong strategy depended on, weakens that strategy without touching it directly.
Developers nerf from data and from feel. Win rates and pick rates show what dominates at each skill level, and a tool that wins too often at high level play warps the meta until every match revolves around it. Nerfs are therefore aimed at the health of the whole game, not at punishing the players who used the strong option fairly while it lasted.
Players react strongly because a nerf devalues invested practice. Hours spent mastering a character feel taxed when that character weakens, even when the change was necessary. Skilled players adapt, move to the next strong option, and the cycle of nerfs and buffs continues for as long as the game is actively balanced.
In play"They will nerf that rifle next patch, because it is winning at every rank right now."