'Oldest' in the Bible

And the three oldest sons of Jesse had gone with Saul to the fight: the names of the three who went to the fight were Eliab, the oldest, and Abinadab the second, and Shammah the third.

And David was the youngest: and the three oldest were with Saul's army.

And Eliab, his oldest brother, hearing what David said to the men, was moved to wrath against David, and said, Why have you come here? Into whose care have you given that little flock of sheep in the waste land? I have knowledge of your pride and the evil of your heart, you have come down to see the fight.

And Saul said to David, Here is my oldest daughter Merab, whom I will give you for your wife: only be strong for me, fighting in the Lord's wars. For Saul said, Let it not be through me that his fate comes to him, but through the Philistines.