'Brother' in the Bible

Now Ahijah, the son of Ahitub (the brother of Ichabod), the son of Phinehas, the son of Eli the priest of Yahweh at Shiloh, was carrying an ephod. The troops did not know that Jonathan had gone.

His oldest brother Eliab heard while he was speaking to the men, {and Eliab became very angry against David} and said, "Why have you come down today, and with whom have you left those few sheep in the wilderness? I know your presumptuousness and the evil of your heart! For you have come down in order to see the battle!"

He said, 'Send me away, please, for our clan sacrifice [is] in the city, and my brother commanded me [to be present]. So then, if I have found favor in your eyes, please let me slip away and see my brothers.' Therefore he has not come to the table of the king."

David answered and said to Ahimelech the Hittite and to Abishai the son of Zeruiah the brother of Joab, saying, "Who will go down with me to Saul, in the camp?" And Abishai said, "I will go down with you."