What does brother mean in the Bible?

Answer 1

At times when it refers to family, it means a natural brother, e.g., "And Jesus, walking by the sea of Galilee, saw two brethren, Simon called Peter, and Andrew his brother, casting a net into the sea..." Matthew 4:18. At other times, it refers to spiritual brothers, as: "But as touching brotherly love ye need not that I write unto you: for ye yourselves are taught of God to love one another." 1 Thessalonians 4;9. Again: "If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?" 1 John 4:20.