The Collaborative International Dictionary of English v.0.48:

Likeness \Like"ness\, n. [AS. gel[imac]cnes.]
   1. The state or quality of being like; similitude;
      resemblance; similarity; as, the likeness of the one to
      the other is remarkable.
      [1913 Webster]

   2. Appearance or form; guise.
      [1913 Webster]

            An enemy in the likeness of a friend. --L'Estrange.
      [1913 Webster]

   3. That which closely resembles; a portrait.
      [1913 Webster]

            [How he looked] the likenesses of him which still
            remain enable us to imagine.          --Macaulay.
      [1913 Webster]

   4. A comparison; parable; proverb. [Obs.]
      [1913 Webster]

            He said to them, Soothly ye shall say to me this
            likeness, Leech, heal thyself.        --Wyclif (Luke
                                                  iv. 23).

   Syn: Similarity; parallel; similitude; representation;
        portrait; effigy.
        [1913 Webster] Likerous

WordNet (r) 3.0 (2006):

likeness
    n 1: similarity in appearance or character or nature between
         persons or things; "man created God in his own likeness"
         [syn: likeness, alikeness, similitude] [ant:
         dissimilitude, unlikeness]
    2: picture consisting of a graphic image of a person or thing
       [syn: likeness, semblance]

Moby Thesaurus II by Grady Ward, 1.0:

199 Moby Thesaurus words for "likeness":
   abstract, abstraction, accordance, affinity, agreement, alikeness,
   alliance, ally, altarpiece, alter ego, analogon, analogousness,
   analogue, analogy, angle, aping, appearance, approach,
   approximation, aspect, assimilation, associate, balance,
   block print, brother, certified copy, close copy, close match,
   closeness, coequality, coextension, cognate, collage, color print,
   community, companion, comparability, comparableness, comparison,
   complement, configuration, conformity, congenator, congener,
   coordinate, copy, copying, correlate, correlative, correspondence,
   correspondent, counterfeit, counterpart, cyclorama, daub,
   dead ringer, diptych, double, drawing, duplicate, ectype, effect,
   effigy, eidolon, engraving, equality, equation, equilibrium,
   equipoise, equipollence, equiponderance, equity, equivalence,
   equivalency, equivalent, evenness, exact likeness, face, facet,
   facsimile, fair copy, faithful copy, fake, fashion, feature,
   fellow, figure, forgery, form, fresco, gestalt, guise, icon,
   identity, idol, ikon, illumination, illustration, image, imago,
   imitation, impression, justice, kindred spirit, levelness, light,
   like, likening, lineaments, living image, living picture, look,
   manner, match, mate, metaphor, mimicking, miniature, mirroring,
   model, montage, mosaic, mural, near duplicate, nearness, obverse,
   painting, panorama, par, parallel, parallelism, parity, pasticcio,
   pastiche, pendant, phase, phasis, phony, photograph, picture,
   poise, portrait, print, proportion, reciprocal, reference,
   reflection, regard, replica, representation, reproduction,
   resemblance, respect, rubbing, sameness, sculpture, second self,
   seeming, semblance, shadow, shape, side, similarity, simile,
   similitude, simulacrum, simulation, sister, slant, soul mate,
   spit and image, spitting image, stained glass window, statue,
   statuette, stencil, still life, style, such, suchlike, symmetry,
   tableau, tally, tapestry, the like of, the likes of, total effect,
   trace, tracing, triptych, twin, twist, uniformity, very image,
   very picture, view, viewpoint, wall painting, wise