brother

The definition of a brother is a boy or man with siblings, or a person who shares something in common with another person.

(noun)

See brother in Webster's New World College Dictionary

a man or boy as he is related to the other children of his parents: sometimes also used of animals
a man or boy related to one by having a parent in common; half brother
a stepbrother
a foster brother
a close male friend who is like a brother
a fellow human being
a male fellow member of the same race, church, profession, organization, etc.: fraternity brother, soul brother
a lay member of a men's religious order
Informal any man: often used as a familiar term of address

Origin: ME < OE brothor < IE base *bhrāter > Goth brothar, L frater, OIr brāthir, Sans bhrātar, Gr phratēr

interjection

Slang used to provide emphasis, often at the beginning of one's remarks

See brother in American Heritage Dictionary 4

noun pl. broth·ers

A male having the same parents as another or one parent in common with another.
pl. also breth·ren (brĕÞˈrən) One who shares a common ancestry, allegiance, character, or purpose with another or others, especially:
a. A kinsman.
b. A fellow man.
c. A fellow member, as of a fraternity, trade union, or panel of judges on a court.
d. A close male friend; a comrade.
e. A fellow African-American man or boy.
pl. also brethren brethren 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. Abbr. Br. or Bro. A member of a men's religious order who is not in holy orders but engages in the work of the order.
b. A lay member of a religious order of men.
c. pl. also brethren brethren A fellow member of the Christian church.