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

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