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

I love how the imagination can dance around these ideas, but the rational part of my brain usually wins over the mystical.

From Salon

The goal, according to authorities, is to "rectify negative emotions" and "create a more civilised and rational online environment".

From BBC

"I hope this is done in a rational way. I strongly believe in a publicly-funded sector, I hope that can be achieved, but let's start with the question: what sector does Scotland need?"

From BBC

But the prosecution argued that Lee had demonstrated rational thought by hiding the children's remains, changing her name and moving back to South Korea, the prosecution said.

From BBC

“Practically and politically, there’s potential” for reform, Motomura said, and he sees a better chance for rational conversations at the local level than in the heat of national debate.

From Los Angeles Times

Related Words

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