rational 

rational - a 
consistent with or based on or using reason; "rational behavior"; "a process of rational inference"; "rational thought" 
capable of being expressed as a quotient of integers; "rational numbers" 
having its source in or being guided by the intellect (as distinguished from experience or emotion); "a rational analysis" 

wordplays

Use the adjective rational to describe people or ideas that operate according to logic or reason. While your brother has an artistic temperament, you have a rational one.

Rational comes from the Latin word rationalis, meaning reasonable or logical. If you're rational, you do things based on logic, as opposed to impulse or whimsy. The original meaning in English was of something endowed with the ability to reason. Before we knew how smart some animals like dolphins are, writers liked to distinguish rational human minds from the supposedly irrational, instinctual minds of animals.

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