From Longman Dictionary of Contemporary Englishrationalra‧tion‧al /ˈræʃənəl/ ●●○AWL adjective 🔊 🔊 1LOGICALrationalthoughts, decisions etc are based on reasons rather than emotions opp irrational 🔊 Parents 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 sensibly opp irrational 🔊 Culley was quite rational at the time of her baby’s death.3formal able to make sensible judgments 🔊 Man is a rational animal. —rationally adverb 🔊 We 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.