rational

adjective ra·tio·nal \ ˈrash-nəl , ˈra-shə-nᵊl \

Updated on: 11 Apr 2018

Definition of rational

1 a : having reason or understanding

b : relating to, based on, or agreeable to reason : reasonable

a rational explanation

rational behavior

2 : involving only multiplication, division, addition, and subtraction and only a finite number of times

3 : relating to, consisting of, or being one or more rational numbers

a rational root of an equation

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rationally

adverb

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rationalness

noun

See rational defined for English-language learners

See rational defined for kids

Examples of rational in a Sentence

human beings are rational creatures
insisted there was a rational explanation for the strange creaking noises and that there were no such things as ghosts

Recent Examples of rational from the Web

Magistretti said that left him with only one rational decision: close the lifts.

— Bloomberg.com, "Bond's Favorite Swiss Ski Resort Loses License to Thrill," 5 Apr. 2018
Both relationships failed, which led her to the rational conclusion: no more Jews for me!

— nicole silverberg, GQ, "Perspective: I Am Tired of Being a White Christian Man's Rebellion," 3 Apr. 2018
There isn’t a rational answer to that question, which is probably why McCarthy didn’t offer one.

— steven ruiz, For The Win, "Why NFL coaches want to keep video footage off the sidelines," 3 Apr. 2018
Because for all the power of algorithms and big data, the decision to buy a product is often rooted in emotional need rather than rational choice.

— marc rey, Fortune, "Commentary: Artificial Intelligence Should Complement, But Never Replace, the Human Connection," 2 Apr. 2018
At the same time, stress chemicals surge to the part of the brain that controls rational thought, often leaving victims to rely instead on habits and reflexes.

— annie sweeney, chicagotribune.com, "Illinois law requires cops to take reports for every sexual assault allegation, get training for sensitivity toward victims," 2 Apr. 2018
My fear is that the current political climate and our ability to discuss things rationally are severely impaired, and that's without factoring in the usual challenges of turning rational ideas into law.

— joi ito, WIRED, "The Paradox of Universal Basic Income," 29 Mar. 2018
Following our instincts in love (or work or finance or buying Rice Krispies) doesn’t always lead to the best rational choice.

— janice kaplan with barnaby marsh, The Cut, "What People Who Are ‘Lucky in Love’ All Have in Common," 21 Mar. 2018
On the other hand, there is a rational basis for worrying about the state of America’s steel industry.

— eric levitz, Daily Intelligencer, "Trump (Finally) Declares His Trade War," 1 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rational.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of rational

Middle English racional, from Anglo-French racionel, from Latin rationalis, from ration-, ratio

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First Known Use: 14th century

See Words from the same year

rational Synonyms

rational

noun

Definition of rational

: something rational; specifically : rational number

First Known Use of rational

1601

RATIONAL Defined for English Language Learners

rational

adjective

Definition of rational for English Language Learners

: based on facts or reason and not on emotions or feelings
: having the ability to reason or think about things clearly

RATIONAL Defined for Kids

rational

adjective ra·tio·nal \ ˈra-shə-nᵊl \

Definition of rational for Students

1 : having the ability to reason

Humans are rational creatures.

2 : based on or showing reason

rational thinking

a rational decision

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rationally

adverb

Medical Dictionary

rational

adjective ra·tio·nal \ ˈrash-nəl, -ən-ᵊl \

medical Definition of rational

1 a : having reason or understanding

b : relating to, based on, or agreeable to reason

a rational explanation

rational behavior

2 : using medical treatments based on reason or general principles —used especially of an ancient school of physicians — compare empirical 1a

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rationally

play \-ē\ adverb

Law Dictionary

rational

adjective ra·tio·nal \ ˈra-shə-nəl \

legal Definition of rational

1 : having reason or understanding

2 : relating to, based on, or guided by reason, principle, fairness, logic, a legitimate state interest, or a consideration of fact

age distinctions are not subject to strict scrutiny, but they must have a rational relationship to a legitimate state interest
—In re J. M., 642 A.2d 1062 (1994)

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