Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “reason”

See all translations

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.
More examples

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.
More examples

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)
What is the pronunciation of reason?
Add Cambridge dictionaries to your browser to your website

Definitions of “reason” in other dictionaries

Word of the Day

be as cold as ice

to be extremely cold

Word of the Day

Cleavage proves divisive in Cambridge’s words of 2014

by Alastair Horne,
December 19, 2014
​​​​ Other dictionaries may choose faddish novelties as their words of the year, but here at Cambridge, we like to do something different. We look for the words that have seen sudden surges in searches over the course of the year – words that have been baffling users of English and driven them

Read More 

cinderella surgery noun

December 15, 2014
cosmetic surgery to the feet We have all heard of people having nose jobs, boob jobs and liposuction – but now a new trend growing in popularity in America: Cinderella surgery.

Read More