What Does it Mean for a Function to be Smooth on the Complex Plane?

[AxiomOfChoice]

What is a "smooth" function?

If someone tells you to consider a "smooth" function on the complex plane, what does that mean, exactly? Does it mean that the partial derivatives of the real and imaginary parts exist and are continuous? Does it mean something else?

 

[quasar987]

Usually, "let f be a smooth function" is an expression people use to be "let f be a function satisfying certain regularity conditions".

Ex: for a smooth enough map f:R^2-->R, we have equality of the mixed partial derivative. Here, smooth means C^2.

Sometimes also, people equate smooth with C^{infinity}.

I've never seen smooth to mean holomorphic though...