The Collaborative International Dictionary of English v.0.48:

Simulacrum \Sim`u*la"crum\, n.; pl. Simulacra. [L. See
   Simulate.]
   A likeness; a semblance; a mock appearance; a sham; -- now
   usually in a derogatory sense.
   [1913 Webster]

         Beneath it nothing but a great simulacrum. --Thackeray.
   [1913 Webster]

WordNet (r) 3.0 (2006):

simulacrum
    n 1: an insubstantial or vague semblance
    2: a representation of a person (especially in the form of
       sculpture); "the coin bears an effigy of Lincoln"; "the
       emperor's tomb had his image carved in stone" [syn: effigy,
       image, simulacrum]

Moby Thesaurus II by Grady Ward, 1.0:

209 Moby Thesaurus words for "simulacrum":
   Prospero, acting, affectation, airiness, ally, alter ego, analogon,
   analogue, angle, appearance, aspect, associate, attitudinizing,
   bluff, bluffing, brother, certified copy, cheat, cheating,
   clinquant, close copy, close match, cognate, color, coloring,
   companion, complement, configuration, congenator, congener,
   coordinate, copy, correlate, correlative, correspondent,
   counterfeit, counterpart, dead ringer, deception, delusion,
   delusiveness, disguise, dissemblance, dissembling, dissimulation,
   double, dummy, duplicate, ectype, effect, effigy, eidolon,
   equivalent, ersatz, exact likeness, facade, face, facet, fair copy,
   faithful copy, fake, fakement, fakery, faking, fallaciousness,
   false air, false appearance, false front, false light, false show,
   falseness, falsity, fashion, feature, feigning, feint, fellow,
   figure, forgery, form, four-flushing, frame-up, fraud, front,
   gestalt, gilt, gloss, guise, hoax, humbug, humbuggery, icon,
   idealization, idol, illusionism, illusionist, illusiveness, image,
   imago, imitation, immateriality, impostor, imposture, impression,
   junk, kindred spirit, light, like, likeness, lineaments,
   living image, living picture, look, magic, magic act, magic show,
   magician, manner, masquerade, match, mate, meretriciousness,
   miniature, mirroring, mock, model, near duplicate, obverse,
   ostentation, outward show, parallel, paste, pasticcio, pastiche,
   pendant, phase, phasis, phony, photograph, picture, pinchbeck,
   playacting, portrait, pose, posing, posture, prestidigitation,
   pretense, pretension, pretext, put-on, put-up job, reciprocal,
   reference, reflection, regard, representation, resemblance,
   respect, ringer, rip-off, rubbing, second self, seeming, semblance,
   shadow, sham, shape, shoddy, show, showing, side, similitude,
   simulation, sister, slant, sleight of hand, sorcerer, sorcery,
   soul mate, specious appearance, speciousness, spit, spit and image,
   spitting image, style, such, suchlike, swindle, tally, the like of,
   the likes of, tinsel, total effect, trace, tracing, twin, twist,
   unactuality, unreality, unsubstantiality, varnish, very image,
   very picture, view, viewpoint, whited sepulcher, window dressing,
   wise