lonesome vs solitary

lonesome is not a noun while solitary is a noun.

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

As adjectives, lonesome and solitary are synonyms defined as:

lonesome and solitary: being the only one; single and isolated from others

Other synonyms of lonesome include lone, only, sole.

lonesome (noun)	solitary (noun)
	one who lives in solitude
	confinement of a prisoner in isolation from other prisoners

lonesome (adjective)	solitary (adjective)
marked by dejection from being alone	being the only one; single and isolated from others
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