'Brother' in the Bible

Paul, an apostle of Christ Jesus by the will of God, and Timothy our brother,To the church of God which is at Corinth with all the saints who are throughout Achaia:

I had no rest for my spirit, not finding Titus my brother; but taking my leave of them, I went on to Macedonia.

We have sent along with him the brother whose fame in the things of the gospel has spread through all the churches;

We have sent with them our brother, whom we have often tested and found diligent in many things, but now even more diligent because of his great confidence in you.

I urged Titus to go, and I sent the brother with him. Titus did not take any advantage of you, did he? Did we not conduct ourselves in the same spirit and walk in the same steps?