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"

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "bottleneck":
   abbreviation, approach, astriction, astringency, asymptote, bar,
   barrier, blank wall, blind alley, blind gut, block, blockade,
   blockage, canal, catch, cecum, cervix, channel, choking,
   choking off, circumscription, clog, coarctation, collision course,
   compactedness, compaction, compression, compressure,
   concentralization, concentration, concourse, concurrence,
   condensation, confluence, conflux, congestion, congress,
   consolidation, constipation, constriction, constringency,
   contraction, contracture, convergence, converging, cordon,
   costiveness, crossing, cul-de-sac, curtailment, curtain, dead end,
   decrease, defile, determent, deterrent, difficulty, diminuendo,
   drawback, embolism, embolus, focalization, focus, funnel, gorge,
   hang-up, hazard, hitch, hourglass, hourglass figure, hub, hurdle,
   impasse, impediment, infarct, infarction, isthmus, jam, joker,
   knitting, meeting, mutual approach, narrow, narrow place,
   narrowing, narrowing gap, narrows, neck, objection, obstacle,
   obstipation, obstruction, obstructive, one small difficulty, pass,
   puckering, pursing, radius, reduction, rub, sealing off,
   shortening, snag, solidification, spokes, stop, stoppage, strait,
   stranglement, strangulation, striction, stricture, stumbling block,
   stumbling stone, systole, tangent, throat, wasp waist, wrinkling