A male person who has the same father and mother with another person, or who has one of them only. In the latter case he is more definitely called a half brother, or brother of the half blood.
- A male having the same parents as another or one parent in common with another.
- One who shares a common ancestry, allegiance, character, or purpose with another or others, especially:
- A kinsman.
- A fellow man.
- A fellow member, as of a fraternity, trade union, or panel of judges on a court.
- A close male friend; a comrade.
- A fellow African-American man or boy.
- Something, such as a corporation or institution, that is regarded as a member of a class: "A station that ... relies on corporate contributions or advertising to survive runs the risk of becoming virtually indistinguishable from its commercial brethren” ( W. John Moore).
- A member of a men's religious order who is not in holy orders but engages in the work of the order.
- A lay member of a religious order of men.
- A fellow member of the Christian church.