A male that has the parent or parents as another. One who shares a common ancestry or allegiance. One who is there when you need him.
Last night me and my brothers walked into a situation to help some other brothers. The brothers I was with knew the brothers we were seeing, but no one knew they weren't being brothers when we got there. One fought to save his brother, the other fought him to save face. The brothers my brothers were trying to help were the best kind of brothers. Brothers who could do anything if only they would do it together. Just like me and my brother.