Bottleneck

What Does Bottleneck Mean?
A point of congestion in a system that occurs when workloads arrive at a given point more quickly than that point can handle them. The inefficiencies brought about by the bottleneck often create a queue and a longer overall cycle time.

Investopedia explains Bottleneck
The term bottleneck refers to the shape of a bottle and the fact that the bottle's neck is the narrowest point, and thus the most likely place for congestion to occur, slowing down the flow of liquid from the bottle. The term is used to describe points of congestion in everything from computer networks to a factory assembly line.

For example, a company whose product is in high demand may see its shipping department receive purchase orders more quickly than the products can be shipped out, thus causing a bottleneck.