/ˈri:zn ||; ˈrizṇ/noun1 [C] a reason (for sth/for doing sth);a reason why.../that... a cause or an explanation for sth that has happened or for sth that sb has done 原因；理由: What's your reason for being so late? 你迟到了这么久有什么原因？Is there any reason why you couldn't tell me this before? 你以前不能告诉我这件事，是不是有什么原因？He said he couldn't come but he didn't give a reason. 他说他不能来，但没有说明原因。The reason (that) I'm phoning you is to ask a favour. 我打电话给你是想请你帮忙。 For some reason they can't give us an answer until next week. 由于某种原因，他们要到下星期才能给我们答复。She left the job for personal reasons. 她因私人理由离职了。
2 [C,U] (a) reason (to do sth);(a) reason (for sth/for doing sth) something that shows that it is right or fair to do sth 正当或合理的理由: I have reason to believe that you've been lying. 我有理由相信你一直在说谎。I think we have reason for complaint. 我认为我们有理由投诉。You have every reason (= you are completely right) to be angry, considering how badly you've been treated. 你受到那样恶劣的对待，完全有理由生气。
3 [U] the ability to think and to make sensible decisions 推理能力；理智；理性: Only human beings are capable of reason. 只有人类才有理性。
4 [U] what is right or acceptable 对的或可接受的东西；道理: I tried to persuade him not to drive but he just wouldn't listen to reason. 我试过劝他不要驾车，但他就是不听道理。I'll pay anything within reason for a ticket. 只要价钱合理，我就会购票。
it stands to reason(
informal 非正式) it is obvious if you think about it 自不待言；理所当然