rationality
Americannoun
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the state or quality of being rational.
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the possession of reason.
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agreeableness to reason; reasonableness.
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the exercise of reason.
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a reasonable view, practice, etc.
noun
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the state or quality of being rational or logical
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the possession or utilization of reason or logic
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a reasonable or logical opinion
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economics the assumption that an individual will compare all possible combinations of goods and their prices when making purchases
Other Word Forms
Derived Forms
Etymology
Origin of rationality
First recorded in 1560–70, rationality is from the Late Latin word ratiōnālitās reasonableness. See rational, -ity
Explanation
Use the noun rationality to refer to the state of being sensible or having good judgment. People may question your rationality if you insist on jumping into freezing water in January and skydiving for the rest of the year. The noun rationality also means the state of being agreeable to reason or being based on logic. If you have to pick a pre-school for your child, you should base your decision on rationality and not an illogical reaction, such as how many of the kids eventually go to Ivy League universities. The newer school may look better on the surface, but the older building may have better teachers, a more interesting curriculum, and be closer to your home.
Vocabulary lists containing rationality
John Nash (1928-2015) Tribute List
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"Simon's Saga," Vocabulary from Episode 21
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167 Vocabulary words from the Supreme Court's DOMA Decision
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"These rules lack humanity and rationality, and they oppress us every day."
From Barron's • Jan. 9, 2026
We comfort the comfortable, and we look for hope in norms and in institutions and in rationality.
From Slate • Dec. 17, 2025
It’s the second factor that often keeps takeover bids alive long after the proposed deals lose their economic rationality.
From Los Angeles Times • Dec. 11, 2025
This work challenges long-held assumptions that rationality, defined as forming and updating beliefs based on evidence, belongs only to humans.
From Science Daily • Nov. 16, 2025
If anything and everything is to be treated as an actor’s judgement then the ideas of truth, rationality and objective reality become meaningless, and we can all be immortal if we choose.
From "The Invention of Science" by David Wootton
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
