Definition of "noumenon"

noumenon

/ˈnuːmənɒn/

noun
plural noumena
1. (from Kantian philosophy on) A thing as it is independent of any conceptualization or perception by the human mind, postulated by practical reason but existing in a condition which is in principle unknowable and unexperienceable.
  Quotations
  The final result of Kant's philosophy, expressed in the concisest terms, was the proposition, so humiliating to human cognition, but, at the same time, so fertile in consequences, that we can know only phenomena, or the outward appearances of things, but not the noumenon, or the thing in itself.
  1871 January, David Asher, “Schopenhauer and Darwinism”, in Journal of Anthropology, volume 1, number 3, page 317
  We have no specific concept of the noumenon, but think of it merely as whatever the object may be apart from the manner in which our knowledge exhibits it.
  1954 July, Bella K. Milmed, “Theories of Religious Knowledge from Kant to Jaspers”, in Philosophy, volume 29, pages 197–198
  That, we have seen, is what prevents the two truths from collapsing into an appearance/reality or phenomenon/noumenon distinction.
  2003 January, Jay L. Garfield, Graham Priest, “Nāgārjuna and the Limits of Thought”, in Philosophy East & West, volume 53, number 1, page 16