smoothness
noun
Definitions
The condition of being smooth; the degree or measure of said condition.
(of a function) The highest order of derivative (the differentiability class) over a given domain.
Example: Smoothness can vary from 0 (for a nondifferentiable function) to infinity (for a smooth function).
(approximation theory, numerical analysis, of a function) The quantity measured by the modulus of smoothness.