Grinding (WoW)

Grinding is a commonly used terms in MMORPG that refers to doing a repetitive action to attain a goal.

The term is very versatile, and can be used to describe pretty much any activity in the game. It is commonly use in the following ways:

Grinding XP: The process of leveling up, usually by focusing on killing mobs rather than Questing.
Grinding Profession: Repetitively crafting the same object to get easy skill up.
Grinding Reputation: Usually implies killing mobs that gives reputation on kill or have a chance of dropping quest items with reputation rewards.
Grinding Honor: Repeatedly going into Battleground.
Grinding Gear: Often applied while going for a certain set of gear, for example, people getting ready for Ragnaros and needing Fire Resistance would often say they were 'Grinding their FR set'.