A virtuous circle or a vicious circle is a complex of events that reinforces itself through a feedback loop toward greater instability. A virtuous circle (or virtuous cycle) has favorable results, and a vicious circle (or vicious cycle) has deleterious results. A virtuous circle can transform into a vicious circle if eventual negative feedback is ignored.
Both circles are complexes of events with no tendency towards equilibrium (at least in the short run). Both systems of events have feedback loops in which each iteration of the cycle reinforces the first (positive feedback). These cycles will continue in the direction of their momentum until an exogenous factor intervenes and stops the cycle. The prefix “hyper” is sometimes used to describe these cycles. The most well known vicious circle is hyperinflation.