big brother

Short definition from Wiktionary

Noun

1. 1
   A sibling's older brother.
2. 2
   Something that is bigger in comparison.
3. 3
   early mobile phones (in China)
4. 4
   Alternative form of Big Brother.

Proper noun

1. 1
   Unwarranted, invasive, and discreet surveillance, especially of a people by its government.
2. 2
   Any omnipresent authority or figurehead representing oppressive control.