brother

A close friend who accompanies his buddies in their activities.

A male with the same parents as someone else.

“my brother still lives with our parents”

Used as a term of address for those male persons engaged in the same movement.

A male person who is a fellow member (of a fraternity or religion or other group).

“none of his brothers would betray him”

(Roman Catholic Church) a title given to a monk and used as form of address.