"Hardcore" is another one of those terms thrown around a lot in relation to gaming, even though the definition is pretty fuzzy. Ditto "casual" on the other end of that supposed spectrum.
I don't own an XBox 360, rarely play FPS games, and don't usually enjoy competitive multiplayer. That rules me out of most of the stereotypes that pop into my head when someone uses the phrase "hardcore gamer". Also, although I find games fun and interesting I've never considered myself particularly skilled at them (though I have improved a lot in recent years).
I don't think that makes me a casual gamer, either (although the fun I've been having recently with Endless Ocean 2 may beg to differ). I'm pretty happy with my average-skilled, variable-genre approach to gaming.