Any arbitrary nonlinear system is not guaranteed to be predictable, it can be chaotic, i.e. it is deterministic but you need infinitely precise knowledge of the

Any arbitrary nonlinear system is not guaranteed to be predictable, it can be chaotic, i.e. it is deterministic but you need infinitely precise knowledge of the initial conditions to predict it (Edit: since small errors in the initial conditions don't necessarily result in small errors in the prediction for nonlinear systems).