brother

(noun) a male with the same parents as someone else. Synonyms: blood brother. Example: "My brother still lives with our parents."

(noun) a male person who is a fellow member (of a fraternity or religion or other group). Example: "None of his brothers would betray him."

(noun) a close friend who accompanies his buddies in their activities. Synonyms: buddy, chum, crony, pal, sidekick.

(noun) used as a term of address for those male persons engaged in the same movement. Synonyms: comrade. Example: "Greetings, comrade!."

(noun) (Roman Catholic Church) a title given to a monk and used as form of address. Synonyms: Brother. Example: "A benedictine brother."