(kā’ os) Theory dealing with the unpredictability that is intrinsic to nonlinear systems. The effects of a small (perhaps unmeasurable) perturbation grow progressively larger and thus prevent long-term predictability. Chaos in a dynamic system can be viewed in terms of diverging time-dependent orbits (paths), which comprise a finite geometric form that is called the chaotic attractor (or strange attractor). The diverging orbits do not repeat exactly and are confined to finite-phase space; the orbits stretch and fold repeatedly. Chaotic attractors are fractals (q.v.). Before a system becomes chaotic, its parameter typically undergoes a cascade of bifurcations in a geometric series.