Why man is a rational being?

hey guys i just want to know why are we considered as a rational being? what does it mean? What if they call you irrational being? what does it mean? i don't really understand this things... please guys i need help?Thanks!
Update: are we considered as a rational being?what if they call you irrational/rational being?what does it mean?
Update 2: Can you site me an example of irrational/rational being..Please..thanks
5 answers 5