solitariness vs solitary

solitariness and solitary both are nouns.

Word	Noun	Adjective	Verb	Adverb
solitariness	Yes	No	No	No
solitary	Yes	Yes	No	No

solitariness (noun)	solitary (noun)
a disposition toward being alone	one who lives in solitude
the state of being alone in solitary isolation	confinement of a prisoner in isolation from other prisoners

solitariness (adjective)	solitary (adjective)
	being the only one; single and isolated from others
	lacking companions or companionship
	of plants and animals; not growing or living in groups or colonies
	devoid of creatures
	characterized by or preferring solitude