Bottleneck literally refers to the top narrow part of a bottle. Figuratively, a bottleneck refers to a low-capacity part of a system that reduces the capacity of the whole system. For example, where a four-lane road's reduced to a two lane road the traffic of all four lanes has to "squeeze" through on two lanes, like squeezing through the neck of a bottle. Other than the narrow part of a bottle a bottleneck may also refer to: Bottleneck (engineering) Bottleneck (logistics) Bottleneck (traffic… (More on Bottleneck)