Source : Webster's Revised Unabridged Dictionary (1913)

Duplicity \Du*plic"i*ty\, n.; pl. {Duplicities}. [F.
   duplicit['e], L. duplicitas, fr. duplex double. See
   {Duplex}.]
   1. Doubleness; a twofold state. [Archaic]

            Do not affect duplicities nor triplicities, nor any
            certain number of parts in your division of things.
                                                  --I. Watts.

   2. Doubleness of heart or speech; insincerity; a sustained
      form of deception which consists in entertaining or
      pretending to entertain one of feelings, and acting as if
      influenced by another; bad faith.

            Far from the duplicity wickedly charged on him, he
            acted his part with alacrity and resolution.
                                                  --Burke.

Source : WordNet®

duplicity
     n 1: a fraudulent or duplicitous representation [syn: {fraudulence}]
     2: acting in bad faith; deception by pretending to entertain
        one set of intentions while acting under the influence of
        another [syn: {double-dealing}]