rational

[rash-uh-nl, rash-nl]

adjective

1. agreeable to reason; reasonable; sensible.

   a rational plan for economic development.

2. having or exercising reason, sound judgment, or good sense.

   a calm and rational negotiator.

   Synonyms: sagacious, judicious, wise, intelligent
   Antonyms: stupid

3. being in or characterized by full possession of one's reason; sane; lucid.

   The patient appeared perfectly rational.

   Antonyms: insane

4. endowed with the faculty of reason.

   rational beings.

5. of, relating to, or constituting reasoning powers.

   the rational faculty.

6. proceeding or derived from reason or based on reasoning.

   a rational explanation.

7. Mathematics.

   1. capable of being expressed exactly by a ratio of two integers.

   2. (of a function) capable of being expressed exactly by a ratio of two polynomials.

8. Classical Prosody.,  capable of measurement in terms of the metrical unit or mora.

noun

1. Mathematics.,  rational number.

rational

/ ˈræʃənəl /

adjective

1. using reason or logic in thinking out a problem

2. in accordance with the principles of logic or reason; reasonable

3. of sound mind; sane

   the patient seemed quite rational

4. endowed with the capacity to reason; capable of logical thought

   man is a rational being

5. maths expressible as a ratio of two integers or polynomials

   a rational number; a rational function

noun

1. maths a rational number

Other Word Forms

• rationally adverb
• rationalness noun
• antirational adjective
• hyperrational adjective
• nonrational adjective
• overrational adjective
• prerational adjective
• quasi-rational adjective
• transrational adjective
• ultrarational adjective
• unrational adjective

Word History and Origins

Origin of rational¹

First recorded in 1350–1400; Middle English racional, from Latin ratiōnālis, equivalent to ratiōn- (stem of ratiō ) reason + -ālis -al ¹

Word History and Origins

Origin of rational¹

C14: from Latin ratiōnālis , from ratiō _reason

Synonym Study

See reasonable.

Example Sentences

It was one of Amorim's more rational statements in a week when he seemed to be adopting a scorched earth policy such is the rollercoaster his emotional state has been.

From BBC

My system presumes a reasonably rational, pragmatic electorate that makes decisions based upon real information.

From Salon

Even if there was no obvious — or rational — solution.

From Los Angeles Times

Indeed, it runs afoul of the entire basis of both political science and economic decision-making: the rational choice model of human behavior, whereby people are assumed to understand their own material interests.

From Salon

"The rational world is behaving irrationally by giving him this welcome," she said.

From BBC

Related Words

• analytical 
• balanced 
• deliberate 
• enlightened 
• impartial 
• intelligent 
• judicious 
• levelheaded 
• logical 
• lucid 
• normal 
• prudent 
• reasonable 
• sane 
• sensible 
• sober 
• stable 
• thoughtful 
• wise