noun
1. : an older brother
2. : one that is like or likened to an older brother:
a. : a man who befriends a delinquent or friendless boy
b. often capitalized both Bs
[ Big Brother, a personification of the power of the state in 1984 (1949) by George Orwell (Eric Blair) died 1950 English author]
(1) : the leader of an authoritarian state or movement
(2) : such a state or movement — called also Big Brotherism