Definition of rational in US English:

rational

adjective

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

    ‘I'm sure there's a perfectly rational explanation’
    • ‘But it does not, by itself, make it rational to believe there is any such a connection.’
    • ‘Nor does it simply rest on the naive distinction between feeling and rational calculation.’
    • ‘Maybe it is simply so beyond our knowing that rational thinking breaks down.’
    • ‘It seems to me that philosophers are often criticized for always demanding rational explanations.’
    • ‘Our capacity for savagery grows as rational thought is overwhelmed by fear, despair, and anger.’
    • ‘He also helped to establish the Roman Empire on a much more rational basis.’
    • ‘Issues such as these are difficult to resolve on a purely rational basis.’
    • ‘The market's savage reaction to most profit warnings is entirely rational.’
    • ‘When persons achieve perfect rationality, they accord with the rational order of a universe ruled by divine reason.’
    • ‘Are you suggesting that rational arguments are not very important?’
    • ‘Hegel develops his rational ontology of gender within a logic of oppositions.’
    • ‘If the substantive law of security could be more rational, so too could the terminology.’
    • ‘But for many people, their faith isn't based around an irrational fervour, and it isn't based around rational logic.’
    • ‘Nationwide regulations would be more rational, and cost allocations more effective.’
    • ‘Breton suggested that rational thought repressed the powers of creativity and imagination and thus was a hindrance to artistic expression.’
    • ‘The ideals of liberty, equality, and fraternity proved inadequate as bases for a fully rational society.’
    • ‘Purely rational arguments often fail to capture potential political audiences, so appeals to emotion are extremely useful.’
    • ‘He sounded like he thought that was a complete, perfectly rational explanation.’
    • ‘Because these choices seem rational in the circumstances does not remove the fact that decisions have been made.’
    • ‘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’
      • ‘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.’
      • ‘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.’
      • ‘How can I be so sure that he'll continue to alienate the rational and sensible voting public with his political decisions?’
      • ‘It was a sensible, reasonable, rational group.’
      • ‘Interestingly, even the mentally deranged humans are rational if not sensible.’
      • ‘Is it only acceptable to be rational and logical?’
      • ‘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.’
      • ‘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.’
      • ‘Unlike the first two, Proviesque rarely displays a logical structure that can be followed by sensible rational people.’
      • ‘However, he isn't entirely rational either according to our understanding of the term.’
      • ‘He wasn't supposed to be rational and logical like this!’
      • ‘"She was one of my favorite teachers, and always seemed so rational.’
      • ‘JACK McConnell came across last week, in the course of a lengthy interview, as rational, down-to-earth, pragmatic and fair.’
      • ‘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.’
      • ‘Do we really believe that people who are capable of such horrifically violent crimes are going to be so coolly logical and rational?’
      • ‘I have a friend, a sensible, rational creature, not outwardly generous, but happy to share a garibaldi if pressed.’
      • ‘Sarah had always been so sensible and rational and now she actually sounded as if she believed what she was saying.’
      • ‘If you're not being rational and logical, I just walk away.’
      • ‘And to a lot of people, I think he came across as the one who was smart and sensible and rational.’
      • ‘David was usually a rational person; always able to maintain a sense of control.’
      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. 1.2 Endowed with the capacity to reason.
      ‘man is a rational being’
      • ‘Kant said that the mind is rational, it is endowed with Reason.’
      • ‘Rationality in creation (like the genetic code) is a logical consequence of a rational God, who speaks to man through his Son.’
      • ‘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.’
      • ‘Since men are rational and egoistic, endowed with the right of property, the composition of output should be determined by consumer sovereignty.’
      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.

    • ‘Boutroux's topics range from rational numbers to an analysis of the notion of a function.’
    • ‘Term formalism can perhaps be extended to the integers and rational numbers, but what are the real numbers supposed to be?’
    • ‘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.’
    • ‘The set of rational numbers is denumerable, that is, it has cardinal number d.’
    • ‘If you stop at this point, you will have a rational number that is very close to the decimal F.’

noun

Mathematics
  • A rational number.

    • ‘He solved the major open problem of approximating algebraic numbers by rationals in 1955.’
    • ‘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.’
    • ‘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.’

Origin

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

Pronunciation

rational

/ˈraSH(ə)n(ə)l//ˈræʃ(ə)n(ə)l/