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1
a
:having reason or understanding
b
:relating to, based on, or agreeable to reason:reasonable
arational 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
arational root of an equation
rationallyadverb
rationalnessnoun
:something rational
specifically:rational number
Synonyms
Examples ofrational in a Sentence
Adjective human beings arerational creatures insisted there was arational explanation for the strange creaking noises and that there were no such things as ghosts
Recent Examples on the Web
Literary Hub, 22 Oct. 2025Theorists could prove that this will not happen if bidders arerational.—Emma Burleigh,Fortune, 21 Oct. 2025Jordana Cepelewicz,Quanta Magazine, 21 June 2024Empirical inquiry—often considered strictly a province of therational—can also be fueled by fervent belief.—Faith Hill,The Atlantic, 6 May 2022See All Example Sentences forrational
Examples are automatically compiled from online sources to show current usage.Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.Send us feedback.
Adjective
Some geomyths, recounted orally over generations, are based on eyewitness experiences, while other accounts are grounded in a keen awareness of local terrains, plusrational and imaginative ideas about the powerful forces of nature.—Literary Hub, 22 Oct. 2025Theorists could prove that this will not happen if bidders arerational.—Emma Burleigh,Fortune, 21 Oct. 2025Noun
For instance, in one group, collect allrationalsthat, when squared, are less than 2; in the other, put all rationals whose squares are greater than 2.—Jordana Cepelewicz,Quanta Magazine, 21 June 2024Empirical inquiry—often considered strictly a province of therational—can also be fueled by fervent belief.—Faith Hill,The Atlantic, 6 May 2022See All Example Sentences forrationalWord History
Phrases Containingrational
Rhymes forrational
Browse Nearby Words
Cite this Entry
“Rational.”Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rational. Accessed 27 Oct. 2025.
Copy CitationKids Definition
rational
1 of 2adjectivera·tio·nalˈrash-nəl 
-ən-ᵊl
1
a
:having the ability to reason
rational beings
b
:relating to, based on, or showing reason:reasonablesense 2
rational behavior
2
:relating to or involving rational numbers
arational fraction
rationallyadverb
-ē
rational
2 of 2noun:something rational
especially:rational number
Medical Definition
rational
adjectivera·tio·nalˈrash-nəl, -ən-ᵊl
1
a
:having reason or understanding
b
:relating to, based on, or agreeable to reason
arational explanation
rational behavior
2
:using medical treatments based on reason or general principles—used especially of an ancient school of physicians compareempiricalsense 1a
Legal Definition
rational
adjectivera·tio·nalˈra-shə-nəl
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 arational relationship to a legitimate state interest—In re J. M., 642 A.2d 1062 (1994)
In re J. M., 642 A.2d 1062 (1994)rationallyadverb
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