noun

 

why the facts about why something happens or why someone does something

I knew Sam was going - that was the reason I went there.

 

right something that makes it right for you to do something

There is every reason to believe the project will be finished on time.

 

ability the ability to think and make good decisions

By this time he'd lost his powers of reason.

 

verb

 

to decide that something is true after considering the facts

We reasoned that it was unlikely he would be a serious threat to the public.