rational

1 of 2

adjective

ra·​tio·​nal ˈrash-nəl How to pronounce rational (audio)
ˈra-shə-nᵊl
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
rationally adverb
rationalness noun

rational

2 of 2

noun

: something rational
specifically : rational number

Examples of rational in a Sentence

Adjective 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 on the Web
Adjective
Anti-intellectualism is much more than just the rejection of the scientific method or rational thought. Matt Motta, Scientific American, 29 Oct. 2024 Military command structures are, by definition, authoritarian, but their effectiveness depends on accurate information and rational discussion among civilian and military leaders. Nina Turner, Newsweek, 29 Oct. 2024
Noun
For instance, in one group, collect all rationals that, when squared, are less than 2; in the other, put all rationals whose squares are greater than 2. Jordana Cepelewicz, Quanta Magazine, 21 June 2024 At the time the database had a little over 3 million elliptic curves over the rationals. Lyndie Chiou, Quanta Magazine, 5 Mar. 2024 See all Example Sentences for rational 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rational.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Adjective

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

First Known Use

Adjective

14th century, in the meaning defined at sense 1a

Noun

1601, in the meaning defined above

Time Traveler
The first known use of rational was in the 14th century

Dictionary Entries Near rational

Cite this Entry

“Rational.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rational. Accessed 5 Nov. 2024.

Kids Definition

rational

1 of 2 adjective
ra·​tio·​nal ˈrash-nəl How to pronounce rational (audio)
-ən-ᵊl
1
a
: having the ability to reason
rational beings
b
: relating to, based on, or showing reason : reasonable sense 2
rational behavior
2
: relating to or involving rational numbers
a rational fraction
rationally
adverb

rational

2 of 2 noun
: something rational
especially : rational number

Medical Definition

rational

adjective
ra·​tio·​nal ˈrash-nəl, -ən-ᵊl How to pronounce rational (audio)
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 sense 1a
rationally adverb

Legal Definition

rational

adjective
ra·​tio·​nal ˈra-shə-nəl How to pronounce rational (audio)
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 interestIn re J. M., 642 A.2d 1062 (1994)
rationality noun
rationally adverb

More from Merriam-Webster on rational

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!