Nonlinear

Adjective

1. Not lying on a straight line.
2. Whose atoms do not lie in a straight line.
3. Having a product of independent variables, or a variable with an exponent not equal to one.
4. 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"