1.Definition: capable of being expressed as a quotient of integers
2.Definition: consistent with or based on or using reason
"Rational behavior", "A process of rational inference", "Rational thought"
3.Definition: having its source in or being guided by the intellect (as distinguished from experience or emotion)
"A rational analysis"
4.Definition: of or associated with or requiring the use of the mind
"The triumph of the rational over the animal side of man"