- a person’s brother by birth.
- a male person bound to another by ties of great friendship.
- something usually associated with or thought to exist inseparably from another thing, quality, circumstance, etc.: Humility is often the blood brother of patience.
- a male established in a close relationship with another male through the performance of a specific ritual, as the commingling of blood.
- a brother by birth
- a man or boy who has sworn to treat another as his brother, often in a ceremony in which their blood is mingled