Noun is a Part of Speech which expresses the Subject spoke of

 Noun is a Part of Speech which expresses the Subject spoke of; as Ink, Paper, Witness.

A Noun is either Substantive, or Adjective.

A Noun Substantive is the Name of a Thing considered simply in itself, and without any Regard to it's Qualities; as a Man, a Woman, a Child.

A Noun Adjective is a Word added to the Noun Substantive, expressing the Circumstance or Quality thereof; as a good Man, an old Woman, a young Child.