This is an irregular feature - both in frequency and oddness - dedicated to a word I came across that I have never previously used.
noumenon (NOO-meh-nahn) n. the intellectual conception of an object as it is ubto itself, not as it is known through the process of perception; an object that is perceived by intellect or reason alone; an object which is perceived by the mind apart from the senses; an object of cognition.
Noumenon comes to us from the German, thanks to Immanuel Kant. He derived the word from the Greek nooumenon, which is the neuter present passive participle of noein, meaning "to perceive by thought." Kant used used noumenon interchangeably with the phrase "a thing in itself" (Ding an sich). The plural form of the word is noumena, while the adjectival form is noumenal, and I have seen the word with the alternate spellings of numenon and nuomenon.
In his Critique of Pure Reason, Kant argued that human understanding is buit upon "concepts of the understanding", or innate intellectual categories that the mind uses to make sense of raw unstructured experience.
This related to his argument that a priori knowledge is transcendental, or based on the form of all possible human experiences, while a posteriori knowledge is empirical, based on the content of an individual's experience.
And that is about all I can dredge up about Kant from the Intro to Philosophy course I took years ago.