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

He said committing to such outlay shortly before announcing major cuts was not "rational".

Read more on BBC

“We do expect it’s going to continue, and we expect the industry will remain rational and disciplined in its approach to pricing,” Daniele said on the earnings call.

Read more on Barron's

“Which means they’re not the most economically rational ones to get into first.”

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“Gold’s meteoric rise and persistent bids seem completely rational in an environment of financial repression and currency debasement,” said Paul Wong, market strategist at Sprott Asset Management, in a report External link Tuesday.

Read more on Barron's

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

Read more on Salon

Related Words

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