The Collaborative International Dictionary of English v.0.48:

Bottleneck \Bot"tle*neck`\
   1. a location or situation in which otherwise rapid progress
      is impeded.
      [PJC]

   2. a point at which road traffic slows due to congestion or
      narrowing of the roadway.
      [PJC]

   3. an impasse.
      [PJC]

   4. a narrowing.

   Syn: constriction.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

bottleneck \bottleneck\ v. t.
   same as obstruct; as, his laziness has bottlenecked our
   efforts to reform the system.
   [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

bottleneck \bottleneck\ v. i.
   to become narrower as one approaches a point; -- said of
   roads; as, right by the bridge, the road bottlenecks.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

bottleneck
    n 1: a narrowing that reduces the flow through a channel [syn:
         constriction, bottleneck, chokepoint]
    2: the narrow part of a bottle near the top
    v 1: slow down or impede by creating an obstruction; "His
         laziness has bottlenecked our efforts to reform the system"
    2: become narrow, like a bottleneck; "Right by the bridge, the
       road bottlenecks"