imitator

from WordNet (r) 3.0 (2006)

imitator
    n 1: someone who (fraudulently) assumes the appearance of
         another [syn: {impersonator}, {imitator}]
    2: someone who copies the words or behavior of another [syn:
       {copycat}, {imitator}, {emulator}, {ape}, {aper}]

from The Collaborative International Dictionary of English v.0.48

Imitator \Im"i*ta"tor\, n. [L.]
   One who imitates.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

33 Moby Thesaurus words for "imitator":
      ape, conformist, copier, copycat, copyist, counterfeiter, cuckoo,
      dissembler, dissimulator, echo, echoer, echoist, faker, forger,
      hypocrite, impersonator, impostor, mime, mimer, mimic, mimicker,
      mocker, mockingbird, monkey, parrot, phony, plagiarist,
      poll-parrot, polly, polly-parrot, poseur, sheep, simulator

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