NOUMENON
noumenon, thing-in-itself
(noun) the intellectual conception of a thing as it is in itself, not as it is known through perception
Source: WordNet® 3.1
Etymology
Noun
noumenon (plural noumena)
(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.
Synonym: thing-in-itself
Antonym: phenomenon
Source: Wiktionary
Nou"me*non, n. Etym: [NL. fr. Gr. (Metaph.)
Definition: The of itself unknown and unknowable rational object, or thing
in itself, which is distinguished from the Ant: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition