adjective

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