This is the confusing range of Reynolds numbers. It is the range where it is difficult to determine the type of flow. It is the range where the type of flow is transiting from laminar to turbulent. In this range of Reynolds number, the flow could either be laminar or turbulent. It isn't easy to determine. It depends on factors like the surface through which the fluid is flowing. The flow could at times be laminar and at times be turbulent. The flow in this range is dynamic and could switch types from time to time. Hence, it's called intermittent flow.