blood-brothers/blood brothers [bluhd-bruhth-er]
noun
1. A person's brother by birth.
2. A male person bound to another by ties of great friendship.
3. Something usually associated with or thought to exist inseparably from another thing, quality, circumstance, etc.: Humility is often the blood brother of patience.
4. A male established in a close relationship with another male through the performance of a specific ritual, as the commingling of blood.
EX. Pets are rarely brothers by blood but I they tend to become blood-brothers, despite rivalry and shared contempt, in order to survive their confinement.
