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English definition of “reason”

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reason

noun uk   /ˈriː.zən/ us  

reason noun (EXPLANATION)

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.by reason of formal because of: He's always asked to these occasions by reason of his position.
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reason noun (JUDGMENT)

[U] the ability of a healthy mind to think and make judgments, especially based on practical facts: We humans believe that we are the only animals to have the power of reason. mainly UK old-fashioned He lost his reason (= became mentally ill) when both his parents were killed in the crash.within reason C2 within the limits of what is acceptable and possible: We can wear anything we like to the office, within reason.
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reason

verb [T] uk   /ˈriː.zən/ us  
to try to understand and to make judgments based on practical facts: [+ (that)] Newton reasoned (that) there must be a force such as gravity I spent hours reasoning out the solution to the puzzle.
Phrasal verbs
(Definition of reason from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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