rational

adjective

1
having its source in or being guided by the intellect (as distinguished from experience or emotion)
a rational analysis
2
of or associated with or requiring the use of the mind
intellectual problems
the triumph of the rational over the animal side of man
3
consistent with or based on or using reason
rational behavior
a process of rational inference
4
capable of being expressed as a quotient of integers
rational numbers

Also useful for “rational”:Unscrambler— Rearrange the letters in “rational”