'Brother' in the Bible

Paul, an Apostle of Jesus Christ by the purpose of God, and Timothy the brother, to the church of God which is in Corinth, with all the saints who are in all Achaia:

I had no rest in my spirit because Titus my brother was not there: so I went away from them, and came into Macedonia.

And with him we have sent a brother whose praise in the good news has gone through all the churches;

And we have sent with them our brother, whose ready spirit has been made clear to us at times and in ways without number, but it is now all the more so because of the certain faith which he has in you.

If any question comes up about Titus, he is my brother-worker, working with me for you; or about the others, they are the representatives of the churches to the glory of Christ.

I gave orders to Titus, and I sent the brother with him. Did Titus make any profit out of you? were we not guided by the same Spirit, in the same ways?