Tuletatav
Tuletatav is an Estonian mathematical term meaning derivable or differentiable. It describes a function that has a derivative at a given point or on an interval. In calculus, a function is said to be tuletatav at x0 if the derivative at x0 exists, denoted f'(x0). If a function is tuletatav at every point of an interval, it is called tuletatav on that interval or simply differentiable on that interval.
Formally, a function f defined on a real interval I is tuletatav at x0 in I when
Examples illustrate the idea: the function f(x) = x^2 is tuletatav on all real numbers with derivative