brother - noun

a male with the same parents as someone else

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

a close friend who accompanies his buddies in their activities

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

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

brother - thesaurus

buddy   chum   comrade   crony   pal   sidekick