Nouns

(n)rational number, rationalan integer or a fraction

Adjectives

(a)rationalconsistent with or based on or using reason“rational behavior”, “a process of rational inference”, “rational thought”
(a)rationalcapable of being expressed as a quotient of integers“rational numbers”
(s)intellectual, rational, noeticof or associated with or requiring the use of the mind“intellectual problems”, “the triumph of the rational over the animal side of man”
(s)rationalhaving its source in or being guided by the intellect (as distinguished from experience or emotion)“a rational analysis”