1rea·son 
/ˈri:zn̩/ noun
plural rea·sons /ˈri:zn̩/ noun 1 [count] : a statement or fact that explains why something is the way it is, why someone does, thinks, or says something, or why someone behaves a certain way
▪ I gave a reason for my absence. ▪ Is there a reason for your strange behavior? ▪ There is a reason why they don't want to come. ▪ I can't give you the report for the simple reason that it isn't yet finished. ▪ She explained her reasons for deciding to change jobs. ▪ He wanted to know the reason for their decision. ▪ “Why don't you want to go to the party?” “No (particular) reason. I just feel like staying home tonight.” ▪ Give me one good reason why I should believe you. ▪ For obvious reasons, we can't do that yet. ▪ For reasons of space, some of the charts and graphs have been omitted from the article. ▪ She resigned for personal reasons. ▪ He is always late, for some/whatever reason. [=he is always late, and no one knows why] ▪ He tends to get upset for no reason. ▪ She did things for no good reason. [=there was no acceptable explanation for her actions] 2 [noncount] : a fact, condition, or situation that makes it proper or appropriate to do something, feel something, etc.
▪ There is no reason [=cause] to panic. ▪ There's no reason for you to feel that way. ▪ I had sufficient/adequate/enough reason [=justification] to leave. ▪ He saw no reason to pursue the issue any further. ▪ They want to try something different, and that's reason enough for the change. ▪ He was found not guilty by reason of insanity. [=not guilty because he was insane when he committed the crime] ▪ We have (every) reason to believe he is lying. ▪ The company fired him with/without reason. [=there was/wasn't a good reason for the company to fire him] ▪ She decided, with reason, to find somewhere else to live. ▪ Poor work conditions are all the more reason to find another job. 3 [noncount] : the power of the mind to think and understand in a logical way
▪ Human beings possess the power of reason. ▪ (old-fashioned) He lost his reason. [=he became insane] 4 [noncount] : ideas and opinions that are fair, sensible, and appropriate
▪ I can't get him to listen to (the voice of) reason. = I can't get him to see reason. ▪ He is not open to reason. [=he is not listening to logical or sensible thinking]
▪ I gave a reason for my absence. ▪ Is there a reason for your strange behavior? ▪ There is a reason why they don't want to come. ▪ I can't give you the report for the simple reason that it isn't yet finished. ▪ She explained her reasons for deciding to change jobs. ▪ He wanted to know the reason for their decision. ▪ “Why don't you want to go to the party?” “No (particular) reason. I just feel like staying home tonight.” ▪ Give me one good reason why I should believe you. ▪ For obvious reasons, we can't do that yet. ▪ For reasons of space, some of the charts and graphs have been omitted from the article. ▪ She resigned for personal reasons. ▪ He is always late, for some/whatever reason. [=he is always late, and no one knows why] ▪ He tends to get upset for no reason. ▪ She did things for no good reason. [=there was no acceptable explanation for her actions]
▪ There is no reason [=cause] to panic. ▪ There's no reason for you to feel that way. ▪ I had sufficient/adequate/enough reason [=justification] to leave. ▪ He saw no reason to pursue the issue any further. ▪ They want to try something different, and that's reason enough for the change. ▪ He was found not guilty by reason of insanity. [=not guilty because he was insane when he committed the crime] ▪ We have (every) reason to believe he is lying. ▪ The company fired him with/without reason. [=there was/wasn't a good reason for the company to fire him] ▪ She decided, with reason, to find somewhere else to live. ▪ Poor work conditions are all the more reason to find another job.
▪ Human beings possess the power of reason. ▪ (old-fashioned) He lost his reason. [=he became insane]
▪ I can't get him to listen to (the voice of) reason. = I can't get him to see reason. ▪ He is not open to reason. [=he is not listening to logical or sensible thinking]
rhyme or reason — see 1rhyme
stand to reason
: to be sensible or understandable
▪ If her friends don't want to go, it stands to reason [=it makes sense] that she won't want to go either.
▪ If her friends don't want to go, it stands to reason [=it makes sense] that she won't want to go either.
within reason
: within reasonable or sensible limits
▪ You can do anything you want, within reason. ▪ The price is within reason.
▪ You can do anything you want, within reason. ▪ The price is within reason.
