Typically applied to online regularly-changed/updated video games.
To "nerf" something means to reduce its '
power' or effectiveness within the game. Often times this is to solve some problem in the game (such as an 'overpowered' weapon/ability or super effective strategy), or to push the players in
one direction or another (such as a new cosmetic/item/character).
Nerfs affect the 'meta' or prevailing strategy/characters/items used to win the game. In this way nerfs also give control to the developer of how the players play the game. i.e. nerfing a commonly used item to discourage the community from playing with it.
Some nerfs can be so drastic they change the very fundamentals of the game, and are often a contributing factor to the size of the playerbase, for good or
bad.
Outside of games, this would again
mean to reduce the things '
power' or 'effectiveness'. The exact analogy that gave birth to this term, is that of a Nerf Gun, compared to a
real gun.
Oh
man, they totally nerfed 'Titans Armor'! Guess I'll stop playing Golem now :/
They nerfed Irelia again?? Oh wait, its actually a buff. <-- (opposite of
nerf)
Great, so now all the free-2-
play guns are nerfed, guess I have to buy some to keep competitive. :(