1. Typically with lower-case initials, one's
older sibling of the male sex.
2.
Figurehead of the totalitarian government of the superstate of
Oceania in George Orwell's final and most famous novel, 1984. Not an "actual" person in the world of the novel, rather a generic middle-aged male face staring out of countless posters, telescreens and so on. The accompanying legend reminds anyone present, "Big Brother is Watching You." Projects an image of the government as
omnipresent, omniscient, and allegedly benign. Shortened to an affectionate "
B.B." in the novel in colloquial speech, and in the daily ritual of the Two Minute Hate.
3. Figurative description of
intrusive government or bureaucracy.
4. At least one television series of the genre known as "reality TV", in which an assorted group of people are obliged for a time to live together in a house being watched through cameras that broadcast their lives together to the watching public. Such a series is typically held as a competition where the public or a smaller group may vote a member out of the house at regular intervals, with a reasonably large cash prize awaiting the resident who stays longest.
Example:
Fred is
Jeremy's big brother.
(Final line of novel): He loved Big Brother.
Big Brother is watching us again, so get your tax forms in on time.
I hope that
harridan Jemima is voted out of the season of Big Brother as soon as possible.