Meaning of “brother” - Learner’s Dictionary

brother

noun [ C ] us uk /ˈbrʌðər/
Extra Examples
I'm very close to my brother.My eldest brother is a doctor.She always felt that her parents favoured her brother.He was bitterly resentful of his brother's success.I had to make a speech at my brother's wedding.
RELATIVE

A1 a boy or man who has the same parents as you:

an older/younger brother
my big/little brother
MEMBER

a man who is a member of the same race, religious group, organization, etc

RELIGION also Brother

a monk (= man who lives in a male religious group):

Brother Paul

(Definition of “brother” from the Cambridge Learner’s Dictionary © Cambridge University Press)