Non-canonical terms of scalar fields

[TimeFall]

Hello! Well, I guess it's all in the title, really. I was reading about k-essence, and it was described as a scalar field having a non-canonical kinetic term. I did a bit of browsing and couldn't find a clear explanation of what, exactly, a non-canonical kinetic term is. Any help would be greatly appreciated! Thanks!

 

[Bill_K]

I just peeked at probably the same paper you're reading, and it says that non-canonical kinetic energy means that instead of using X = ½∂_μφ ∂^μφ for the kinetic energy, he uses some function of it, F(X).