One's colleague ("brother" in the same craft, occupation, or society). / (India) One's wife's sister's husband.

(Christianity) A layman who is a member of a brotherhood without the intention to become a priest.

comrade in arms (fellow combatant or soldier)

(informal) A little brother.

(informal) A fellow African American man

Alternative spelling of milk brother

A male milk sibling.

A fellow police officer

A full brother: a brother born to the same mother and father, as distinguished from half brothers (uterine brothers), step-brothers, or 'brothers' established through relationships such as wardship.

A man who is simultaneously brother and husband to his wife.