rational

The word “rational” means based on clear reasoning and logic rather than emotion. In plain terms, sensible and logical, or (in math) expressible as a fraction.

“Rational” is pronounced RASH-nuhl (/ˈɹæʃ(ə)nəl/ in IPA).

Here is “rational” used in a sentence: “Try to make a rational decision instead of an impulsive one.”

The opposite of “rational” — its antonyms — are absurd, irrational, nonsensical, arbitrary and arational.

“Rational” is an adjective.

The word “rational” comes from Latin. From Latin rationalis, "of reason," from ratio, "reason, calculation.".

“Rational” is a fairly common word in modern English, usually learned at around the B1 level.

“Rational” has 2 distinct senses listed in this dictionary. The most common is: based on clear reasoning and logic rather than emotion.

Rational emphasizes that something is based on clear reasoning and logic rather than emotion, as in "a rational decision." Reasonable emphasizes fairness and moderation, as in "a reasonable price" or "a reasonable request." A rational argument is logically sound; a reasonable one is fair and sensible.

Rational is an adjective meaning based on logic rather than emotion, while rationale is a noun meaning the set of reasons or logical basis behind a decision. You might explain the rationale for a plan and hope your audience finds it rational. The two are often confused because they look and sound similar.

In mathematics, a rational number is any number that can be written as a fraction of two whole numbers, such as 1/2, 3 (which equals 3/1), or 0.75 (which equals 3/4). Numbers that cannot be written this way, such as pi or the square root of 2, are called irrational numbers.

The most direct opposite of rational is irrational, meaning not based on clear reasoning or logic. Depending on context, illogical, absurd, or arbitrary can also serve as opposites. In mathematics, irrational specifically describes a number that cannot be expressed as a fraction of two whole numbers.