The Collaborative International Dictionary of English v.0.48:

faker \fak"er\, n. [Sometimes erroneously written fakir.]
   1. One who fakes something; as
      (a) a thief.
      (b), a peddler of petty things.
      (c) a workman who dresses things up. [Slang]
          [Webster 1913 Suppl.]

   2. a person who makes deceitful pretenses.

   Syn: imposter, impostor, pretender, fake, fraud, sham,
        pseudo, pseud, role player.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

faker
    n 1: a person who makes deceitful pretenses [syn: imposter,
         impostor, pretender, fake, faker, fraud, sham,
         shammer, pseudo, pseud, role player]