rationalness vs rational

rationalness and rational both are nouns.

Word	Noun	Adjective	Verb	Adverb
rationalness	Yes	No	No	No
rational	Yes	Yes	No	No

rationalness (noun)	rational (noun)
the quality of being consistent with or based on logic	an integer or a fraction

rationalness (adjective)	rational (adjective)
	consistent with or based on or using reason
	capable of being expressed as a quotient of integers
	having its source in or being guided by the intellect (as distinguished from experience or emotion)
	of or associated with or requiring the use of the mind