brother is an English word that means brother.
The word brother indicates a degree of relatedness, of two people who have the same father and mother. However there are other expressions, such as stepbrother or half brother, which means half-brother, when two people have only one parent in common. Still within the family, a brother-in-law means brother in law.
At the religious context, the word brother or brother serves to describe a man who has the same religious beliefs and who is part of the same church.
Also, the word brother is used in English and Portuguese to designate a very close friend who is even seen as a brother. Often the word brother is shortened to "bro". Ex: Hey bro! Are we playing soccer today? - Hey brother/bro! Are we going to play football today?
big brother
The expression big brother means "big brother" but is often used to describe an older brother.
The expression gained great popularity through the novel Nineteen Eighty Four (or 1984) by George Orwell (pseudonym of Eric Arthur Blair), published in 1948. In this novel, the
Big Brother (character inspired by Josef Stalin) controls the people like an older brother, abusing their authority and not respecting the privacy of citizens. In this society oppressed by totalitarianism, there are signs on the street that say, "Big Brother has his eye on you."Later, Orwell's work was the inspiration for the creation of the reality show known worldwide as Big Brother, where participants are monitored 24 hours a day.