Hardcore

Hardcore is generally a term for MMORPG players who play a lot (30+ hours a week), prefer challenging play (PvP or cutting edge PvE), and don't like rulesets that make the game easier. Often used in contrast to the term casual.

Blizzard has made more effort than many companies to make World of Warcraft friendly to the casual player, but definitely has lots of content for group-oriented, hardcore players with their focus on large raid dungeons (20-, 25-, and 40-man) and battleground PvP for more solo-oriented hardcore players.