The Collaborative International Dictionary of English v.0.48:

Deception \De*cep"tion\, n. [F. d['e]ception, L. deceptio, fr.
   decipere, deceptum. See Deceive.]
   1. The act of deceiving or misleading. --South.
      [1913 Webster]

   2. The state of being deceived or misled.
      [1913 Webster]

            There is one thing relating either to the action or
            enjoyments of man in which he is not liable to
            deception.                            --South.
      [1913 Webster]

   3. That which deceives or is intended to deceive; false
      representation; artifice; cheat; fraud.
      [1913 Webster]

            There was of course room for vast deception.
                                                  --Motley.

   Syn: Deception, Deceit, Fraud, Imposition.

   Usage: Deception usually refers to the act, and deceit to the
          habit of the mind; hence we speak of a person as
          skilled in deception and addicted to deceit. The
          practice of deceit springs altogether from design, and
          that of the worst kind; but a deception does not
          always imply aim and intention. It may be undesigned
          or accidental. An imposition is an act of deception
          practiced upon some one to his annoyance or injury; a
          fraud implies the use of stratagem, with a view to
          some unlawful gain or advantage.
          [1913 Webster]

WordNet (r) 3.0 (2006):

deception
    n 1: a misleading falsehood [syn: misrepresentation, deceit,
         deception]
    2: the act of deceiving [syn: deception, deceit,
       dissembling, dissimulation]
    3: an illusory feat; considered magical by naive observers [syn:
       magic trick, conjuring trick, trick, magic,
       legerdemain, conjuration, thaumaturgy, illusion,
       deception]

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "deception":
   acting, affectation, airy nothing, appearance, artifice,
   attitudinizing, autism, befooling, bluff, bluffing, bubble, burial,
   burying, casuistry, cheat, cheating, chicane, chicanery, chimera,
   clouding, color, coloring, concealedness, concealment, covering,
   covering up, covertness, cunning, darkening, daydream, deceit,
   deceptiveness, defrauding, deluded belief, delusion, dereism, dirt,
   disguise, dishonesty, dissemblance, dissembling, dissimulation,
   double-dealing, dream, dream vision, dreamland, dreamworld, dupery,
   duping, duplicity, equivocation, facade, face, fake, fakement,
   fakery, faking, false air, false belief, false front, false show,
   falsity, feigning, feint, flam, four-flushing, fraud, front, gilt,
   gloss, guile, gulling, gyp, hallucination, hanky-panky, hiddenness,
   hiding, hoax, hoodwinking, humbug, humbuggery, hypocrisy,
   ignis fatuus, illusion, impose, imposture, indirection, interment,
   intrigue, invisibility, knavery, manipulation, masking, masquerade,
   meretriciousness, mirage, misbelief, misconception, mystification,
   obscuration, obscurement, occultation, ostentation, outward show,
   overreaching, pipe dream, playacting, pose, posing, posture,
   pretense, pretension, pretext, putting away, representation, ride,
   rip-off, ruse, screening, secrecy, secretion, seeming, self-deceit,
   self-deception, self-delusion, sell, semblance, sham,
   sharp practice, show, simulacrum, simulation, snow job, sophism,
   sophistry, speciousness, spoof, spuriousness, stratagem,
   subterfuge, tergiversation, treachery, trick, trickery, trip,
   uncommunicativeness, vapor, varnish, wile, window dressing,
   wrong impression