NOUN (3)

1. a series of sentinels or of military posts enclosing or guarding some place or thing;

2. cord or ribbon worn as an insignia of honor or rank;

3. adornment consisting of an ornamental ribbon or cord;

The Collaborative International Dictionary of English v.0.48:

Cordon \Cor"don\ (k[^o]r"d[o^]n; F. k[^o]r`d[^o]N"), n. [F., fr.
   corde. See Cord.]
   1. A cord or ribbon bestowed or borne as a badge of honor; a
      broad ribbon, usually worn after the manner of a baldric,
      constituting a mark of a very high grade in an honorary
      order. Cf. Grand cordon.
      [1913 Webster]

   2. The cord worn by a Franciscan friar. --Sir E. Sandys.
      [1913 Webster]

   3. (Fort.) The coping of the scarp wall, which projects
      beyong the face of the wall a few inches.
      [1913 Webster]

   4. (Mil.) A line or series of sentinels, or of military
      posts, inclosing or guarding any place or thing.
      [1913 Webster]

   5. A rich and ornamental lace or string, used to secure a
      mantle in some costumes of state.
      [1913 Webster]

   Cordon sanitaire (k?r`d?n" s?`n?`t?r") [F., sanitary
      cordon], a line of troops or military posts around a
      district infected with disease, to cut off communication,
      and thus prevent the disease from spreading. Also used
      figuratively, of a group of neutral states that forms a
      barrier between two hostile states.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cordon
    n 1: a series of sentinels or of military posts enclosing or
         guarding some place or thing
    2: cord or ribbon worn as an insignia of honor or rank
    3: adornment consisting of an ornamental ribbon or cord

Moby Thesaurus II by Grady Ward, 1.0:

141 Moby Thesaurus words for "cordon":
   advance guard, armed guard, bank guard, beleaguer, beset, besiege,
   block, blockade, blue ribbon, bolt, bottleneck, bound, box in,
   cage, catch, chamber, close in, coast guard, compass, contain,
   coop, coop in, coop up, cordon bleu, cordon off, cordon sanitaire,
   cordoning off, corral, cull out, curtain, decoration,
   decoration of honor, determent, deterrent, difficulty, divide,
   drawback, encircle, enclose, encompass, enshrine, fence in,
   garrison, garter, ghettoize, gin, goalie, goalkeeper, goaltender,
   gold star, grand cordon, guard, guarder, guardsman, hang-up,
   hazard, hedge in, hem in, hitch, house in, hurdle, impound,
   imprison, incarcerate, include, inlying picket, insulate, isolate,
   isolation, jail, jailer, joker, keep apart, keep aside, kennel,
   lay aside, leaguer, mew, mew up, objection, obstacle, obstruction,
   obstructive, one small difficulty, order, ornament, outguard,
   outpost, pen, pen in, pick out, picket, pocket, put aside,
   quarantine, quarantine flag, rail in, rear guard, red ribbon,
   riband, ribbon, riddle, rope off, rub, sanitary cordon, screen,
   seal off, seclude, seclusion, security guard, segregate,
   segregation, separate, separation, set apart, set aside, shrine,
   shut in, shut up, sieve, sift, snag, sort out, stable, star,
   stumbling block, stumbling stone, surround, thrash, thresh,
   train guard, van, vanguard, wall in, warder, winnow, wrap, yard,
   yard up, yellow flag, yellow jack