Nouns

(n)constriction, bottleneck, chokepointa narrowing that reduces the flow through a channel
(n)bottleneckthe narrow part of a bottle near the top

Verbs

(v)bottleneckslow down or impede by creating an obstruction“His laziness has bottlenecked our efforts to reform the system”
(v)bottleneckbecome narrow, like a bottleneck“Right by the bridge, the road bottlenecks”