WordNet (r) 3.0 (2006):

logjam
    n 1: any stoppage attributable to unusual activity; "the
         legislation ran into a logjam"
    2: an immovable mass of logs blocking a river

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "logjam":
   afterthought, arch dam, backstop, bamboo curtain, bank, bar,
   barrage, barrier, bear-trap dam, beaver dam, bind, block, blockage,
   boom, breakwater, breastwork, brick wall, buffer, bulkhead,
   bulwark, bureaucratic delay, cofferdam, dam, defense, delay,
   delayage, delayed reaction, detention, dike, ditch, double take,
   dragging, earthwork, embankment, fence, gate, gravity dam, groin,
   halt, hang-up, hindrance, holdup, hydraulic-fill dam, interim,
   iron curtain, jam, jetty, lag, lagging, leaping weir, levee,
   milldam, moat, mole, moratorium, mound, obstruction, paperasserie,
   parapet, pause, portcullis, rampart, red tape, red-tapeism,
   red-tapery, reprieve, respite, retardance, retardation, roadblock,
   rock-fill dam, seawall, shutter dam, slow-up, slowdown, slowness,
   stay, stay of execution, stone wall, stop, stoppage, suspension,
   tie-up, time lag, wait, wall, weir, wicket dam, work