rational

Universal Words adjective 1 (of behaviour, ideas, etc.) based on reason rather than emotions: a rational argument / choice / decision * rational analysis / thought * There is no rational explanation for his actions. 2 (of a person) able to think clearly and make decisions based on reason rather than emotions: No rational person would ever behave like that. OPPIRRATIONAL rationality noun [U]: the rationality of his argument rationally adverb: to act / behave / think rationally * She argued her case calmly and rationally.