The Collaborative International Dictionary of English v.0.48:

Peculiar \Pe*cul"iar\, n.
   1. That which is peculiar; a sole or exclusive property; a
      prerogative; a characteristic.
      [1913 Webster]

            Revenge is . . . the peculiar of Heaven. --South.
      [1913 Webster]

   2. (Eng. Canon Law) A particular parish or church which is
      exempt from the jurisdiction of the ordinary.
      [1913 Webster]

   Court of Peculiars (Eng. Law), a branch of the Court of
      Arches having cognizance of the affairs of peculiars.
      --Blackstone.

   Dean of peculiars. See under Dean, 1.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

COURT OF PECULIARS, Eng. eccl. law. The name of a court, which is a branch
of, and annexed to, the. court of arches.
     2. It has jurisdiction over all those parishes dispersed through the
province of Canterbury, in the midst of other dioceses. In the other
peculiars, the jurisdiction is exercised by commissaries. 1 Phill. R. 202,
n.
     3. There are three sorts of peculiars 1. Royal peculiars. 3 Phill. R.
245. 2. The second sort are those in which the bishop has no concurrent
jurisdiction, and are exempt from his visitation. 3. The third are subject
to the bishop's visitation, and liable to his superintendence and
jurisdiction. 3 Phill. R. 245; Skinn. R. 589.