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English definition of “rational”

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rational

adjective  /ˈræʃ·ə·nəl/ us  
showing clear thought or reason: a rational decision Obviously, he wasn’t rational.
rationally
adverb [not gradable]  /ˈræʃ·ə·nəl·i/ us  
It’s hard to behave rationally at such times.
(Definition of rational from the Cambridge Academic Content Dictionary © Cambridge University Press)
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