rational
Americanadjective
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agreeable to reason; reasonable; sensible.
a rational plan for economic development.
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having or exercising reason, sound judgment, or good sense.
a calm and rational negotiator.
- Synonyms:
- sagacious, judicious, wise, intelligent
- Antonyms:
- stupid
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being in or characterized by full possession of one's reason; sane; lucid.
The patient appeared perfectly rational.
- Antonyms:
- insane
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endowed with the faculty of reason.
rational beings.
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of, relating to, or constituting reasoning powers.
the rational faculty.
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proceeding or derived from reason or based on reasoning.
a rational explanation.
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Mathematics.
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capable of being expressed exactly by a ratio of two integers.
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(of a function) capable of being expressed exactly by a ratio of two polynomials.
-
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Classical Prosody. capable of measurement in terms of the metrical unit or mora.
noun
adjective
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using reason or logic in thinking out a problem
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in accordance with the principles of logic or reason; reasonable
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of sound mind; sane
the patient seemed quite rational
-
endowed with the capacity to reason; capable of logical thought
man is a rational being
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maths expressible as a ratio of two integers or polynomials
a rational number; a rational function
noun
Related Words
See reasonable.
Other Word Forms
Etymology
Origin of rational
First recorded in 1350–1400; Middle English racional, from Latin ratiōnālis, equivalent to ratiōn- (stem of ratiō ) reason + -ālis -al 1
Explanation
Use the adjective rational to describe people or ideas that operate according to logic or reason. While your brother has an artistic temperament, you have a rational one. Rational comes from the Latin word rationalis, meaning reasonable or logical. If you're rational, you do things based on logic, as opposed to impulse or whimsy. The original meaning in English was of something endowed with the ability to reason. Before we knew how smart some animals like dolphins are, writers liked to distinguish rational human minds from the supposedly irrational, instinctual minds of animals.
Vocabulary lists containing rational
Positive Adjectives to Describe People
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Arithmetic
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The Number System
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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.
The company’s all-in approach to government contracting makes it a favorite in Washington, said Luke Rahbari, portfolio manager of the Rational Equity Armor Fund, which holds Palantir stock.
From Barron's • Mar. 2, 2026
For anyone curious to meet the musicians who made them, “Four Rational People” is a decent introduction.
From The Wall Street Journal • Feb. 19, 2026
Rational thought has apparently left the building – and probably did so right after Elvis did.
From Salon • Aug. 1, 2024
Rational minds aren’t looking at the Mariners’ three consecutive losses as a surefire sign that they’ll regress after last year’s drought-breaking season.
From Seattle Times • Apr. 2, 2023
The conditions of truth and the errors incident to the attempt to determine it, are the business of the Logic of Rational Belief, commonly entitled Inductive Logic.
From Logic, Inductive and Deductive by Minto, William
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.
