The Collaborative International Dictionary of English v.0.48:

Propriety \Pro*pri"e*ty\, n.; pl. Proprieties. [F.
   propri['e]t['e], L. proprietas, fr. proprius one's own,
   proper. See Property, Proper.]
   1. Individual right to hold property; ownership by personal
      title; property. [Obs.] "Onles this propriety be exiled."
      --Robynson (More's Utopia).
      [1913 Webster]

            So are the proprieties of a wife to be disposed of
            by her lord, and yet all are for her provisions, it
            being a part of his need to refresh and supply hers.
                                                  --Jer. Taylor.
      [1913 Webster]

   2. That which is proper or peculiar; an inherent property or
      quality; peculiarity. [Obs.] --Bacon.
      [1913 Webster]

            We find no mention hereof in ancient zoographers, .
            . . who seldom forget proprieties of such a nature.
                                                  --Sir T.
                                                  Browne.
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   3. The quality or state of being proper; suitableness to an
      acknowledged or correct standard or rule; consonance with
      established principles, rules, or customs; fitness;
      appropriateness; as, propriety of behavior, language,
      manners, etc. "The rule of propriety," --Locke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

propriety
    n 1: correct or appropriate behavior [syn: propriety,
         properness, correctitude] [ant: improperness,
         impropriety]