'Brother' in the Bible

Paul, apostle of Jesus Christ by God's will, and the brother Timotheus, to the assembly of God which is in Corinth, with all the saints who are in the whole of Achaia.

I had no rest in my spirit at not finding Titus my brother; but bidding them adieu, I came away to Macedonia.

but we have sent with him the brother whose praise is in the glad tidings through all the assemblies;

And we have sent with them our brother whom we have often proved to be of diligent zeal in many things, and now more diligently zealous through the great confidence he has as to you.

I begged Titus, and sent the brother with him: did Titus at all make gain of you? have we not walked in the same spirit? have we not in the same steps?