'Brother's' in the Bible

Then the Lord said to Cain, "Where is your brother Abel?" And he replied, "I don't know! Am I my brother's guardian?"

But the Lord said, "What have you done? The voice of your brother's blood is crying out to me from the ground!

So now, you are banished from the ground, which has opened its mouth to receive your brother's blood from your hand.

Two sons were born to Eber: One was named Peleg because in his days the earth was divided, and his brother's name was Joktan.

Live with him for a little while until your brother's rage subsides.

Stay there until your brother's anger against you subsides and he forgets what you did to him. Then I'll send someone to bring you back from there. Why should I lose both of you in one day?"

Then Judah said to Onan, "Have sexual relations with your brother's wife and fulfill the duty of a brother-in-law to her so that you may raise up a descendant for your brother."

But Onan knew that the child would not be considered his. So whenever he had sexual relations with his brother's wife, he withdrew prematurely so as not to give his brother a descendant.