Adjective
designating or involving an equation whose terms are not of the first degree
Source: WordNetnonlinear interactions almost always make the behavior of the aggregate more complicated than would be predicted by summing or averaging. John Henry Holland
Human history is highly nonlinear and unpredictable. Michael Shermer
People take the longest possible paths, digress to numerous dead ends, and make all kinds of mistakes. Then historians come along and write summaries of this messy, nonlinear process and make it appear like a simple, straight line. Dean Kamen
Of course the word chaos is used in rather a vague sense by a lot of writers, but in physics it means a particular phenomenon, namely that in a nonlinear system the outcome is often indefinitely, arbitrarily sensitive to tiny changes in the initial condition. Murray Gell-Mann
The economy is a nonlinear fractal system, where the smallest scales are linked to the largest, and the decisions of the central bank are affected by the gut instincts of the people on the street. David Orrell
Not only in research, but also in the everyday world of politics and economics, we would all be better off if more people realised that simple nonlinear systems do not necessarily possess simple dynamical properties. Robert M. May