The Collaborative International Dictionary of English v.0.48:

Cork \Cork\, v. t. [imp. & p. p. Corked (k[^o]rkt); p. pr. &
   vb. n. Corking.]
   1. To stop with a cork, as a bottle.
      [1913 Webster]

   2. To furnish or fit with cork; to raise on cork.
      [1913 Webster]

            Tread on corked stilts a prisoner's pace. --Bp.
                                                  Hall.
      [1913 Webster]

   Note: To cork is sometimes used erroneously for to calk, to
         furnish the shoe of a horse or ox with sharp points,
         and also in the meaning of cutting with a calk.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cork \Cork\ (k[^o]rk), n. [Cf. G., Dan., & Sw. kork, D. kurk;
   all fr. Sp. corcho, fr. L. cortex, corticis, bark, rind. Cf.
   Cortex.]
   1. The outer layer of the bark of the cork tree (Quercus
      Suber), of which stoppers for bottles and casks are made.
      See Cutose.
      [1913 Webster]

   2. A stopper for a bottle or cask, cut out of cork.
      [1913 Webster]

   3. A mass of tabular cells formed in any kind of bark, in
      greater or less abundance.
      [1913 Webster]

   Note: Cork is sometimes used wrongly for calk, calker;
         calkin, a sharp piece of iron on the shoe of a horse or
         ox.
         [1913 Webster]

   Cork jackets, a jacket having thin pieces of cork inclosed
      within canvas, and used to aid in swimming.

   Cork tree (Bot.), the species of oak (Quercus Suber of
      Southern Europe) whose bark furnishes the cork of
      commerce.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cork
    n 1: outer bark of the cork oak; used for stoppers for bottles
         etc.
    2: (botany) outer tissue of bark; a protective layer of dead
       cells [syn: phellem, cork]
    3: a port city in southern Ireland
    4: the plug in the mouth of a bottle (especially a wine bottle)
       [syn: cork, bottle cork]
    5: a small float usually made of cork; attached to a fishing
       line [syn: bob, bobber, cork, bobfloat]
    v 1: close a bottle with a cork [syn: cork, cork up] [ant:
         uncork]
    2: stuff with cork; "The baseball player stuffed his bat with
       cork to make it lighter"

Moby Thesaurus II by Grady Ward, 1.0:

212 Moby Thesaurus words for "cork":
   Carling float, air, asphyxiate, balsa, balsa raft, bar, bark,
   bedarken, besmirch, bind, black, blacken, blackwash, block,
   block up, blockade, blot, blotch, bob, bonnet, boom, bottle up,
   box up, bubble, bung, buoy, cage, cap, caulk, ceil, censor, chaff,
   charcoal, check, check valve, chink, chip, choke, choke off,
   choke up, clamp down on, clog, clog up, cloister, cobweb, cock,
   coif, confine, congest, constipate, constrain, coop, coop in,
   coop up, cork up, cortex, cover, crack down on, crib, crown, crush,
   dam, dam up, damp down, darken, denigrate, detain, dinge, dome,
   down, drown, dust, ebonize, encage, enclose, epicarp, ether,
   extinguish, fairy, faucet, feather, fence in, fill, fill up, float,
   flue, fluff, foam, foul, froth, fuzz, gag, gossamer, hat, hem in,
   hold, hold down, hold in, hold in custody, hold in restraint, hood,
   immure, impound, inhibit, ink, jam, jump on, keep, keep down,
   keep in, keep in custody, keep in detention, keep under, kill, lid,
   life buoy, life preserver, life raft, lock in, maintain, melanize,
   mew, mew up, mote, murk, muzzle, nigrify, obstipate, obstruct,
   oversmoke, pack, peel, peeling, peg, pen, pen up, phellum, pin,
   plug, plug up, pontoon, pound, pour water on, preserve, put down,
   quash, quell, quench, raft, rail in, repress, restrain, restrict,
   retain, rind, roof, roof in, save, save up, sea cock, seal up,
   shackle, shade, shadow, shut down on, shut in, shut up, silence,
   sit down on, sit on, skin, smash, smirch, smoke, smother, smudge,
   smut, smutch, soot, spigot, spike, spile, spill, sponge, spume,
   squash, squelch, stanch, stay, stench, stifle, stop, stop up,
   stopgap, stopper, stopple, strangle, straw, stuff, stuff up,
   stultify, subdue, suffocate, suppress, surfboard, tap, thistledown,
   throttle, tip, top, valve, wall in