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Definition of rational in English:

rational

Pronunciation /ˈraSH(ə)n(ə)l/ /ˈræʃ(ə)n(ə)l/

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adjective

  • 1Based on or in accordance with reason or logic.

    ‘I'm sure there's a perfectly rational explanation’
    • ‘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.’
    • ‘It seems to me that philosophers are often criticized for always demanding rational explanations.’
    • ‘When persons achieve perfect rationality, they accord with the rational order of a universe ruled by divine reason.’
    • ‘He also helped to establish the Roman Empire on a much more rational basis.’
    • ‘He sounded like he thought that was a complete, perfectly rational explanation.’
    • ‘If the substantive law of security could be more rational, so too could the terminology.’
    • ‘Nationwide regulations would be more rational, and cost allocations more effective.’
    • ‘Issues such as these are difficult to resolve on a purely rational basis.’
    • ‘Purely rational arguments often fail to capture potential political audiences, so appeals to emotion are extremely useful.’
    • ‘Our capacity for savagery grows as rational thought is overwhelmed by fear, despair, and anger.’
    • ‘The market's savage reaction to most profit warnings is entirely rational.’
    • ‘Breton suggested that rational thought repressed the powers of creativity and imagination and thus was a hindrance to artistic expression.’
    • ‘Are you suggesting that rational arguments are not very important?’
    • ‘Maybe it is simply so beyond our knowing that rational thinking breaks down.’
    • ‘But it does not, by itself, make it rational to believe there is any such a connection.’
    • ‘Because these choices seem rational in the circumstances does not remove the fact that decisions have been made.’
    • ‘Nor does it simply rest on the naive distinction between feeling and rational calculation.’
    • ‘I can get so bloody angry sometimes; it just doesn't seem rational.’
    logical, reasoned, well reasoned, sensible, reasonable, cogent, coherent, intelligent, wise, judicious, sagacious, astute, shrewd, perceptive, enlightened, clear-eyed, clear-sighted, commonsensical, common-sense, well advised, well grounded, sound, sober, prudent, circumspect, politic
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    1. 1.1(of a person) able to think clearly, sensibly, and logically.
      ‘Andrea's upset—she's not being very rational’
      • ‘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.’
      • ‘On behalf of all dog owners and all sensible, rational people who still have common sense in this country, we say that this is bad legislation and that we are against it.’
      • ‘Anyway, enough of the justification of why a supposedly logical and rational person such as myself could take interest in something as supposedly trivial as astrology.’
      • ‘It was a sensible, reasonable, rational group.’
      • ‘If you're not being rational and logical, I just walk away.’
      • ‘Interestingly, even the mentally deranged humans are rational if not sensible.’
      • ‘This guy used to be a dyed in the wool reactionary but I've noticed that lately he's been well… pretty sensible and rational.’
      • ‘Even during the day, when he felt he was able to be more rational, he did not think it unlikely that he would be shot or crucified for his crime.’
      • ‘David was usually a rational person; always able to maintain a sense of control.’
      • ‘And to a lot of people, I think he came across as the one who was smart and sensible and rational.’
      • ‘JACK McConnell came across last week, in the course of a lengthy interview, as rational, down-to-earth, pragmatic and fair.’
      • ‘Sarah had always been so sensible and rational and now she actually sounded as if she believed what she was saying.’
      • ‘How can I be so sure that he'll continue to alienate the rational and sensible voting public with his political decisions?’
      • ‘He wasn't supposed to be rational and logical like this!’
      • ‘Is it only acceptable to be rational and logical?’
      • ‘Do we really believe that people who are capable of such horrifically violent crimes are going to be so coolly logical and rational?’
      • ‘However, he isn't entirely rational either according to our understanding of the term.’
      • ‘"She was one of my favorite teachers, and always seemed so rational.’
      lucid, coherent, sane, in one's right mind, able to reason clearly, able to think clearly, of sound mind, in possession of all one's faculties
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    2. 1.2Endowed with the capacity to reason.
      ‘man is a rational being’
      • ‘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.’
      • ‘As rational beings, then we are duty bound to be morally upright.’
      • ‘He saw Man as essentially rational and able to see right from wrong.’
      • ‘Rationality in creation (like the genetic code) is a logical consequence of a rational God, who speaks to man through his Son.’
      intelligent, thinking, discriminating, reasoning
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  • 2Mathematics
    (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.

    ‘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?’
    • ‘If you stop at this point, you will have a rational number that is very close to the decimal F.’
    • ‘Boutroux's topics range from rational numbers to an analysis of the notion of a function.’

noun

Mathematics

  • A rational number.

    ‘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.’
    • ‘Dedekind's brilliant idea was to represent the real numbers by such divisions of the rationals.’
    • ‘He solved the major open problem of approximating algebraic numbers by rationals in 1955.’

Origin

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