OP stands for overpowered and describes champions, items, or strategies that are noticeably stronger than the game’s intended balance. Something considered OP often wins fights too easily or creates overwhelming advantages, making it difficult for opponents to respond even with good Positioning or smart Pathing.
When an element of the game becomes OP, it usually attracts attention from Riot and may receive a later Nerf to bring it back in line with the rest of the roster. The community commonly uses the term to highlight anything that feels unfair or excessively dominant in the current patch.