anxious vs anxiousness

anxious is not a noun while anxiousness is a noun.

Word	Noun	Adjective	Verb	Adverb
anxious	No	Yes	No	No
anxiousness	Yes	No	No	No

anxious (noun)	anxiousness (noun)
	a feeling of mild anxiety about possible developments
	(psychiatry) a relatively permanent state of worry and nervousness occurring in a variety of mental disorders, usually accompanied by compulsive behavior or attacks of panic

anxious (adjective)	anxiousness (adjective)
eagerly desirous
causing or fraught with or showing anxiety