What is Reason ?
Reason is (noun) 1. a thing which explains why something has happened The airline gave no reason for the plane’s late arrival. The boss asked him for the reason why he was behind with his work. for some reason in a way which you cannot explain For some reason (or other) the builders sent us two invoices. 2. the power of thought He used reason to solve the mathematical problem. 3. the ability to make sensible judgments She wouldn’t listen to reason. it stands to reason it is reasonable It stands to reason that he wants to join his father’s firm. to see reason to see that someone’s argument is right or reasonable She was going to report her neighbours to the police, but in the end we got her to see reason. within reason to a sensible degree, in a sensible way The children get £5 pocket money each week, and we let them spend it as they like, within reason. (verb) 1. to think or to plan something carefully and sensibly He reasoned that any work is better than no work, so he took the job. If you take the time to reason it out, you’ll find a solution to the problem. 2. to reason with someone to try to calm someone, to try to make someone change his mind The policewoman tried to reason with the man who was holding a knife.
source: Easier English, Student Dictionary Upper Intermediate Level