'Brother' in the Bible

Paul, an apostle of Jesus Christ, through the will of God, and Timotheus the brother, to the assembly of God that is in Corinth, with all the saints who are in all Achaia:

I have not had rest to my spirit, on my not finding Titus my brother, but having taken leave of them, I went forth to Macedonia;

and we sent with him the brother, whose praise in the good news is through all the assemblies,

and we sent with them our brother, whom we proved in many things many times being diligent, and now much more diligent, by the great confidence that is toward you,

I entreated Titus, and did send with him the brother; did Titus take advantage of you? in the same spirit did we not walk? -- did we not in the same steps?