The Collaborative International Dictionary of English v.0.48:

Impropriety \Im`pro*pri"e*ty\, n.; pl. Improprieties. [L.
   improprietas; cf. F. impropri['e]t['e]. See Improper.]
   1. The quality of being improper; unfitness or unsuitableness
      to character, time place, or circumstances; as,
      impropriety of behavior or manners.
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   2. That which is improper; an unsuitable or improper act, or
      an inaccurate use of language.
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            But every language has likewise its improprieties
            and absurdities.                      --Johnson.
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            Many gross improprieties, however authorized by
            practice, ought to be discarded.      --Swift.
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