nonlinear
nonlinear , adjective
1.
(Mathematics) Not depictable graphically as a straight line; not changing by a constant amount for each unit of time, distance, or other independent variable. Opposite of linear.
2.
(Mathematics) Containing variables of greater than the first degree; -- of an equation. Opposite of linear.
3.
(Physics) Represented by equations containing variables of greater than the first degree; -- of physical processes or relationships. Opposite of linear.