Source : Webster's Revised Unabridged Dictionary (1913)

Impiety \Im*pi"e*ty\, n.; pl. {Impieties}. [L. impietas, fr.
   impius impious; cf. F. impi['e]t['e]. See {Impious},
   {Piety}.]
   1. The quality of being impious; want of piety; irreverence
      toward the Supreme Being; ungodliness; wickedness.

   2. An impious act; an act of wickednes.

            Those impieties for the which they are now visited.
                                                  --Shak.

   Syn: Ungodliness; irreligion; unrighteousness; sinfulness;
        profaneness; wickedness; godlessness.

Source : WordNet®

impiety
     n : unrighteousness by virtue of lacking respect for a god [syn:
          {impiousness}] [ant: {piety}]