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English definition of “reason”

reason

noun (EXPLANATION)    /ˈriː.zən/
A2 [C or U] the cause of an event or situation or something that provides an excuse or explanation: The reason for the disaster was engine failure, not human error. [+ question word] The reason why grass is green was a mystery to the little boy. [+ (that)] The reason (that) I'm calling is to ask a favour.not standard The reason I walked out was because I was bored. [+ to infinitive] The police have (every good) reason to believe that he is guilty. She was furious, and with reason (= with good cause). For some reason/For reasons best known to himself (= for reasons no one else knows about) he's decided to leave his job.Motives and reasonsReasons and explanations by reason of formal because of: He's always asked to these occasions by reason of his position.Connecting words which introduce a cause or reason Grammar:Reason thatWe use reason that before a clause. We often omit that, especially in statements. Reason that is less common and slightly more formal than reason why:See moreGrammar:Reason + to-infinitiveWe can use reason with a to-infinitive:See moreGrammar:ReasonSee moreGrammar:Reason forWe use reason for + noun phrase, not reason of:See moreGrammar:Reason whyWe use reason why before a clause. We often omit why, especially in statements:See more
(Definition of reason noun (EXPLANATION) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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