What do you mean by unidentified risk?

Risk that has not been identified or recognized but has some effect on the likelihood of achieving our objective. These risks are dangerous because they could cause serious issues with the overll operations. Hence management should always should be vary about this risks.

Unidentified risks are the risks that seem impossible to find.

Part of this is to reflect on the types of uncertainty, namely the known knowns (change control), known unknowns (risk management), unknown knowns (planning & communication errors) and the unknown unknowns (unexpected events and changes)

A model to describe these four types of uncertainty is the Cynefin Framework which is divided in to the following: Order, unorder and disorder. Unorder is furthermore divided in to the complex domain and the complicated domain, while order is divided in to the chaotic domain and the simple domain.