Nonlinear

adjective

1. (of a set of points) Not lying on a straight line.
2. (of a molecule) Whose atoms do not lie in a straight line.
3. (of a function) Having a product of independent variables, or a variable with an exponent not equal to one.
4. (of a system) Whose output is not directly proportional to its input.
5. Erratic and unpredictable; tending to jump back and forth.

   "a film with a nonlinear plot"