The Collaborative International Dictionary of English v.0.48:

Inclosure \In*clo"sure\ (?; 135), n. [See Inclose,
   Enclosure.] [Written also enclosure.]
   [1913 Webster]
   1. The act of inclosing; the state of being inclosed, shut
      up, or encompassed; the separation of land from common
      ground by a fence.
      [1913 Webster]

   2. That which is inclosed or placed within something; a thing
      contained; a space inclosed or fenced up.
      [1913 Webster]

            Within the inclosure there was a great store of
            houses.                               --Hakluyt.
      [1913 Webster]

   3. That which incloses; a barrier or fence.
      [1913 Webster]

            Breaking our inclosures every morn.   --W. Browne.
      [1913 Webster]

WordNet (r) 3.0 (2006):

inclosure
    n 1: something (usually a supporting document) that is enclosed
         in an envelope with a covering letter [syn: enclosure,
         inclosure]
    2: the act of enclosing something inside something else [syn:
       enclosure, enclosing, envelopment, inclosure]