unreasonable vs irrational

unreasonable is not a noun while irrational is a noun.

Word	Noun	Adjective	Verb	Adverb
unreasonable	No	Yes	No	No
irrational	Yes	Yes	No	No

unreasonable (noun)	irrational (noun)
	a real number that cannot be expressed as a rational number

unreasonable (adjective)	irrational (adjective)
not reasonable; not showing good judgment	not consistent with or using reason
beyond normal limits	real but not expressible as the quotient of two integers