What is "adnoun"

Adnoun \Ad"noun`\, n. [Pref. ad- + noun.] (Gram.) An adjective, or attribute. [R.]
--Coleridge.

n. 1 (context grammar English) an adjective used as a noun (sensu stricto), an absolute adjective 2 (context grammar dated English) an adjective

n. an adjective used as a noun; "`meek' in `blessed are the meek' is an adnoun"

Adnoun is a linguistic term used with two different meanings.