The Collaborative International Dictionary of English v.0.48:

Congest \Con*gest"\, v. t. [L. congestus, p. p. of congere to
   bring together; con- + gerere. See Gerund.]
   [1913 Webster]
   1. To collect or gather into a mass or aggregate; to bring
      together; to accumulate.
      [1913 Webster]

            To what will thy congested guilt amount?
                                                  --Blackmore.
      [1913 Webster]

   2. (Med.) To cause an overfullness of the blood vessels (esp.
      the capillaries) of an organ or part.
      [1913 Webster]

WordNet (r) 3.0 (2006):

congest
    v 1: become or cause to become obstructed; "The leaves clog our
         drains in the Fall"; "The water pipe is backed up" [syn:
         clog, choke off, clog up, back up, congest,
         choke, foul] [ant: unclog]

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "congest":
   bar, bind, block, block up, blockade, brim, bung, caulk, charge,
   chink, chock, choke, choke off, choke up, clog, clog up, close,
   compact, compress, concentrate, condense, consolidate, constipate,
   cork, cover, cram, crowd, dam, dam up, densen, densify, drench,
   fill, fill to overflowing, fill up, foul, freight, glut,
   gluttonize, gorge, jam, jam-pack, lade, load, obstipate, obstruct,
   occlude, overburden, overcharge, overfeed, overfill, overlade,
   overload, overstuff, overweight, pack, pad, plug, plug up, press,
   ram down, ram in, satiate, saturate, soak, solidify, spile,
   squeeze, stanch, stay, stench, stop, stop up, stopper, stopple,
   stuff, stuff up, supercharge, supersaturate, surcharge, surfeit,
   top off, wad, weight