The Collaborative International Dictionary of English v.0.48:

Emblem \Em"blem\, n. [F. embl[`e]me, L. emblema, -atis, that
   which is put in or on, inlaid work, fr. Gr. ? a thing put in
   or on, fr. ? to throw, lay, put in; ? in + ? to throw. See
   In, and Parable.]
   1. Inlay; inlaid or mosaic work; something ornamental
      inserted in a surface. [Obs.] --Milton.
      [1913 Webster]

   2. A visible sign of an idea; an object, or the figure of an
      object, symbolizing and suggesting another object, or an
      idea, by natural aptness or by association; a figurative
      representation; a typical designation; a symbol; as, a
      balance is an emblem of justice; a scepter, the emblem of
      sovereignty or power; a circle, the emblem of eternity.
      "His cicatrice, an emblem of war, here on his sinister
      cheek." --Shak.
      [1913 Webster]

   3. A picture accompanied with a motto, a set of verse, or the
      like, intended as a moral lesson or meditation.
      [1913 Webster]

   Note: Writers and artists of the 17th century gave much
         attention and study to the composition of such emblems,
         and many collections of them were published.

   Syn: Sign; symbol; type; device; signal; token.

   Usage: Sign, Emblem, Symbol, Type. Sign is the
          generic word comprehending all significant
          representations. An emblem is a visible object
          representing another by a natural suggestion of
          characteristic qualities, or an habitual and
          recognized association; as, a circle, having no
          apparent beginning or end, is an emblem of eternity; a
          particular flag is the emblem of the country or ship
          which has adopted it for a sign and with which it is
          habitually associated. Between emblem and symbol the
          distinction is slight, and often one may be
          substituted for the other without impropriety. See
          Symbol. Thus, a circle is either an emblem or a
          symbol of eternity; a scepter, either an emblem or a
          symbol of authority; a lamb, either an emblem or a
          symbol of meekness. "An emblem is always of something
          simple; a symbol may be of something complex, as of a
          transaction . . . In consequence we do not speak of
          actions emblematic." --C. J. Smith. A type is a
          representative example, or model, exhibiting the
          qualities common to all individuals of the class to
          which it belongs; as, the Monitor is a type of a class
          of war vessels.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Emblem \Em"blem\, v. t. [imp. & p. p. Emblemed; p. pr. & vb.
   n. Embleming.]
   To represent by an emblem; to symbolize. [R.]
   [1913 Webster]

         Emblemed by the cozening fig tree.       --Feltham.
   Emblematic

WordNet (r) 3.0 (2006):

emblem
    n 1: special design or visual object representing a quality,
         type, group, etc.
    2: a visible symbol representing an abstract idea [syn:
       emblem, allegory]

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "emblem":
   adumbration, allegory, armory, attribute, badge, badge of office,
   badges, baton, blazonry, brassard, button, cap and gown, case,
   case in point, chain, chain of office, charactery, cipher,
   class ring, coat, cockade, collar, conventional symbol, crest,
   cross, decoration, demonstration, device, dress, eagle, emblems,
   ensigns, example, exemplar, exemplification, explanation, exponent,
   fasces, figurehead, fleur-de-lis, hammer and sickle, heraldry,
   iconology, ideogram, illustration, insignia, instance, lapel pin,
   livery, logo, logogram, logotype, love knot, mace, mantle,
   markings, medal, mortarboard, object lesson, old school tie,
   pictogram, pin, regalia, relevant instance, representation,
   representative, ring, rose, school ring, seal, shamrock,
   sigillography, sign, skull and crossbones, sphragistics, staff,
   swastika, symbol, symbolic system, symbolism, symbolization,
   symbology, tartan, thistle, tie, token, totem, totem pole, type,
   typical example, uniform, verge, wand