From King Dictionary of Contemporary Englishrationalra‧tion‧al /ˈræʃənəl/ ●●○AWL adjective1LOGICALrationalthoughts, decisions etc are based on reasons rather than emotionsOPP irrationalParents need to be fully informed so they can make a rational decision.I’m sure there’s a rational explanation for all this.It’s impossible to have a rational conversation with him.2SENSIBLEa rational person is able to think calmly and sensiblyOPP irrationalCulley was quite rational at the time of her baby’s death.3formal able to make sensible judgmentsMan is a rational animal. —rationally adverbWe were too shocked to think rationally. —rationality /ˌræʃəˈnæləlti/ noun [uncountable]COLLOCATIONSnounsa rational explanationI told myself that there must be some simple, rational explanation.a rational decision/choiceThe patient was incapable of making a rational decision.a rational approachWe must adopt a rational approach when dealing with this problem.a rational analysisEmotions are running so high that any rational analysis of the situation is difficult.rational thoughtBabies were thought to be incapable of rational thought.rational argumentNuclear weapons are so absurd that rational argument about their use is scarcely possible.a rational conversation/discussionLet's all calm down and have a rational discussion.adverbsperfectly rationalI'm sure there's a perfectly rational explanation.

Examples from the Corpus

rational• The talk was lively and, compared to Morrison's drivel, refreshingly rational.• Many of the patients have long histories of drugabuse, and they're not always rational.• People's behaviour isn't always purely rational.• Such beliefsserve to explain the system to its members: they make social inequality appear rational and reasonable.• We're looking for someone with a rationalapproach to dealing with problems.• rational behavior• From a rationalchoiceperspective, you would be rather foolish to vote in a presidentialelection.• It should be seen as seven functionalstages of the budgetary process which take place in a political or rationalcontext.• Education helps us to make rational decisions.• Should they, then, be branded as spurious designators and banished from rationaldiscourse?• There is no rationalexplanation for Melanie Hawkin's disappearance.• There must be some rational explanation for this apparently bizarrephenomenon.• Let's try and discuss this like two rationalhumanbeings.• How can a rational man be taken in by these arguments?• Consequently rational members of organizations are more likely to stay loyal and inactive than to be vocalparticipants.• There appears to be no rationalmotive for the attack.• Exactly how a rational person will solve it we shall show later on.• No rational person would have agreed to those terms.• Taking action to defend yourself is a completely rationalreaction if you're being attacked.rational explanation• In any case, Amiss's mind was racing, grappling with a situation devoid of any rational explanation.• The subsequentreferences by the deceased to £17,000 as the value of his portfolio were not the subject of any rational explanation.• Through their variousplights, the drama questions a world where feminineideals regularly defyrational explanation.• There was a rational explanation for all this and, when Carolarrived, he'd discover what it was.• This is the mystery of sin which has no rational explanation, for it is ultimately and radically inexplicable.• Only now have scientists begun to offer rational explanations for this phenomenon.• Either way, there has to be some rational explanation of Clinton's conduct.• I told myself that there must be some simple, rational explanation, something Illingworth had overlooked.Originrational(1300-1400)Latinrationalis, from ratio; → RATIO