Well IDK, with me "casual" is more or less accurate so I refer to myself as that.
I try my best, I tackle hard content but I am a dusty old crone at this point in my life (by Internet standards) and no longer have the time or stamina to dedicate to hard mode, extreme raiding. I did some high end raiding in WoW but...those days are behind me.
It's a little sad that "casual" has come to mean "bad" to so many people. Casuals can be good at the game, we just don't consume the content at the same rate as hardcore players and that's fine, isn't it?