The Collaborative International Dictionary of English v.0.48:

Privity \Priv"i*ty\, n.; pl. Privities (-t[i^]z). [From
   Privy, a.: cf. F. privaut['e] extreme familiarity.]
   [1913 Webster]
   1. Privacy; secrecy; confidence. --Chaucer.
      [1913 Webster]

            I will unto you, in privity, discover . . . my
            purpose.                              --Spenser.
      [1913 Webster]

   2. Private knowledge; joint knowledge with another of a
      private concern; cognizance implying consent or
      concurrence.
      [1913 Webster]

            All the doors were laid open for his departure, not
            without the privity of the Prince of Orange.
                                                  --Swift.
      [1913 Webster]

   3. A private matter or business; a secret. --Chaucer.
      [1913 Webster]

   4. pl. The genitals; the privates.
      [1913 Webster]

   5. (Law) A connection, or bond of union, between parties, as
      to some particular transaction; mutual or successive
      relationship to the same rights of property.
      [1913 Webster]