noumenon

noumenon
    n 1: the intellectual conception of a thing as it is in itself,
         not as it is known through perception [syn: {noumenon},
         {thing-in-itself}]
    

Noumenon \Nou"me*non\ (nou"m[-e]*n[o^]n), n. [NL. fr. Gr. ? the
   thing perceived, p. pr. pass. of ? to perceive, ? the mind.]
   (Metaph.)
   The of itself unknown and unknowable rational object, or
   thing in itself, which is distinguished from the {phenomenon}
   through which it is apprehended by the senses, and by which
   it is interpreted and understood; -- so used in the
   philosophy of Kant and his followers.
   [1913 Webster]
    

NOUMENON, n.  That which exists, as distinguished from that which
merely seems to exist, the latter being a phenomenon.  The noumenon is
a bit difficult to locate; it can be apprehended only be a process of
reasoning -- which is a phenomenon.  Nevertheless, the discovery and
exposition of noumena offer a rich field for what Lewes calls "the
endless variety and excitement of philosophic thought."  Hurrah
(therefore) for the noumenon!