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rational Syllabification: ra·tion·al
Pronunciation: /ˈraSH(ə)n(ə)l/

Definition of rational in English:


1Based on or in accordance with reason or logic: I’m sure there’s a perfectly rational explanation
More example sentences
  • Hegel develops his rational ontology of gender within a logic of oppositions.
  • But for many people, their faith isn't based around an irrational fervour, and it isn't based around rational logic.
  • The ideals of liberty, equality, and fraternity proved inadequate as bases for a fully rational society.
logical, reasoned, sensible, reasonable, cogent, intelligent, judicious, shrewd, common-sense, commonsensical, sound, prudent;
down-to-earth, practical, pragmatic
1.1(Of a person) able to think clearly, sensibly, and logically: Andrea’s upset—she’s not being very rational
More example sentences
  • Unlike the first two, Proviesque rarely displays a logical structure that can be followed by sensible rational people.
  • To be honest, I once thought about having another woman, but I did not do it because I was able to be rational, I did not want to take any risks.
  • I have a friend, a sensible, rational creature, not outwardly generous, but happy to share a garibaldi if pressed.
normal, balanced, grounded, lucid, coherent
informal all there
1.2Endowed with the capacity to reason: man is a rational being
More example sentences
  • Kant said that the mind is rational, it is endowed with Reason.
  • Since men are rational and egoistic, endowed with the right of property, the composition of output should be determined by consumer sovereignty.
  • There is implanted in every rational being the capacity to distinguish the true from the false, to weigh the evidence, and to confront the world without illusions.
intelligent, thinking, reasoning;
cerebral, logical, analytical
formal ratiocinative
2 Mathematics (Of a number, quantity, or expression) expressible, or containing quantities that are expressible, as a ratio of whole numbers. When expressed as a decimal, a rational number has a finite or recurring expansion.
Example sentences
  • The set of rational numbers is denumerable, that is, it has cardinal number d.
  • His idea was that every real number r divides the rational numbers into two subsets, namely those greater than r and those less than r.
  • Term formalism can perhaps be extended to the integers and rational numbers, but what are the real numbers supposed to be?


Mathematics Back to top  
A rational number.
Example sentences
  • The construction of the reals from the integers proceeds in several stages: first axiomatize the positive integers, then construct negative from positive integers, then rationals from integers, and finally reals from rationals.
  • Thus a set that includes the rationals has been put into a systematic one-to-one correspondence with the natural numbers.
  • She then extended the function to the negative rationals.


Late Middle English (in the sense 'having the ability to reason'): from Latin rationalis, from ratio(n-) 'reckoning, reason' (see ratio).

Words that rhyme with rational

irrational, national, passional
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