The term 'Narrow Entrance' can be summarized as a 'BOTTLENECK, ' which is a situation where the capacity of a certain route or passage is limited, usually due to its size. This can cause a delay or disruption in the flow of traffic or goods. It is often used to describe a situation where there is a limited amount of resources available, such as a limited number of people who can enter a building or a limited amount of goods that can pass through a certain route.