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

The price war has drawn the ire of Beijing, with China’s top market regulator earlier this year calling for the companies to engage in “rational” competition.

Read more on The Wall Street Journal

For some, withdrawing into a small personal space and lowering expectations seems like a rational, even self-protective, response.

Read more on MarketWatch

The sculptures lovingly sanctify a keystone’s rational but enigmatic contradiction of mechanics and function.

Read more on Los Angeles Times

Blanc will reveal the truth, proclaiming his choice to “kneel at the altar of the rational.”

Read more on Los Angeles Times

“No rational trader would take that trade. Yet we wonder why labor force participation lags. It’s not a mystery. It’s math.”

Read more on MarketWatch

Related Words

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