Definition of rational in English:
rational
Syllabification: ra·tion·alPronunciation: /ˈraSHənl, ˈraSHnəl
/
adjective
 1Based on or in accordance with reason or logic: I’m sure there’s a perfectly rational explanationMore 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, commonsense, commonsensical, sound, prudent; downtoearth, practical, pragmatic  1.1(Of a person) able to think clearly, sensibly, and logically: Andrea’s upset—she’s not being very rationalMore 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.
sane, compos mentis, in one's right mind, of sound mind; normal, balanced, grounded, lucid, coherent• informal all there  1.2Endowed with the capacity to reason: man is a rational beingMore 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.
 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.More 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?
noun
Mathematics Back to top A rational number.More 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 onetoone correspondence with the natural numbers.
 She then extended the function to the negative rationals.
Derivatives

rationality
 More example sentences
 Truth, science, intellectual inquiry and rationality are inextricably bound together.
 His threat lay in his cold rationality and his overwhelming intellectual authority.
 Our judgements are constrained by rationality to the extent that we cannot just label any movement a cult by pure whim.

rationally
 More example sentences
 From this perspective you will be able to think much more clearly and rationally.
 Her philosophy was that everything could be explained logically and rationally.
 Anger clearly breeds stupidity, but let us try to think rationally this Sunday.
Pronunciation: /ˌraSHəˈnalətē/
noun
Pronunciation: /ˈraSHənlē, ˈraSHnəlē/
adverb
Origin
late Middle English (in the sense 'having the ability to reason'): from Latin rationalis, from ratio(n) 'reckoning, reason' (see ratio).
More definitions of rational
Definition of rational in: The British & World English dictionary
 The English Synonyms
 The US English Synonyms