Brother: The Hebrew word is used in various senses in the Old Testament, as,

1. Any kinsman, and not a mere brother; e.g. nephew, (Genesis 13:8; 14:16) husband, (Solomon 4:9)
2. One of the same tribe. (2 Samuel 19:13)
3. Of the same people, (Exodus 2:11) or even of a cognate people. (Numbers 20:14)
4. An ally. (Amos 1:9)
5. Any friend, (Job 5:15)
6. One of the same office. (1 Kings 9:13)
7. A fellow man. (Leviticus 19:17)
8. Metaphorically of any similarity, as in (Job 30:19) The word adelphos has a similar range of meanings in the New Testament.